NEW YORK -- Thirty years past his first high school band, the Echoes, it's still rock-and-roll to Billy Joel. "The question is: Can rock-and-roll grow up and still have its potency, its essence -- which is the wild abandon of youth, sex, freedom, the flouting of convention?" Joel asks, a few hours before 20,000 people -- most of them comfortably middle-aged -- fill Madison Square Garden for one of six straight shows that sold out in a matter of hours.

Tastefully grizzled at 44, Billy Joel is not exactly the portrait of wanton, rebellious youth. He's clad in an Armani suit, eating a lobster salad in a tony hotel lounge. And tonight, after the concert, he'll be ferried by helicopter back to his East Hampton, N.Y., estate and his wife, supermodel Christie Brinkley, and his 7-year-old daughter, Alexa Ray. It's a long way from Hicksville -- the Long Island town Joel grew up in -- but such are the perks of a 20-year career that has seen Joel burst onto the Top 40 pop charts 32 times.

Right now, though, Joel is less Piano Man than Answer Man. The question remains rock-and-roll... .

"Can it grow up? Some of it can," Joel suggests. "The basics of rock-and-roll we bring with us through our lives anyway. I'm still as crazy as I ever was, I just know more stuff. I can be as wildly romantic as I was at 19, I'm just a little more guarded."

That's not exactly true. Joel's 15th album, "River of Dreams" -- which opened at No. 1 and sold 2 million copies in its first month -- may be his most unguarded moment. In these new songs he moves from a very personal rage to spiritual catharsis; it's telling that the word "faith" appears in six of the album's 10 songs.

"I don't think I've ever put together one completely confessional album," says Joel, who performs at USAir Arena tomorrow and Tuesday and again Nov. 3. "It's painful -- ripping myself open to sift through my guts and find out what it is I'm feeling. I don't like dwelling within myself for a long time.

"In every album, there's a certain amount of me, a certain amount of observation of people I know, of life in general -- journalism, editorializing -- it's a potpourri. But, yes, this album pretty much dealt with me, myself and I. They say, 'Write what you know,' and for a year I was thinking about what was going on with me."

What was going on with Billy Joel was the anger and frustration that had been building for years in the fiscal corners of his career. He didn't start the ire: Joel blames that on former manager and confidant Frank Weber, whom he is suing for alleged fraud and mismanagement. According to Joel, Weber bilked him out of $30 million in songwriting royalties, concert receipts and other income. Weber calls the charges ludicrous.

Joel's bitter feelings are barely disguised on "The Great Wall of China," a cut on "River of Dreams" that includes the lines "You take a piece of whatever you touch/ too many pieces means you're touching too much" and "Your role was protective/ your soul was too defective/ some people just don't have a heart to be broken." The song proved to be a psychological breakthrough, Joel says; it was the starting point for an album that ultimately moved from the hurt of betrayal to the affirmation of faith.

"This is by no means 'the lawsuit album,' " Joel says with a chuckle. "There's only one song that really deals with that particular issue, and there's even a mocking element to it. I brought some 'On the Waterfront' dialogue into it: 'Charlie, you was my buddy, you shoulda looked out for me.' "

It was not the first time Joel made emotional and professional miscalculations. In 1982, he'd gone through a vituperative divorce with his first wife, Elizabeth, who had also served as his manager. Subsequently, Joel turned his career over to Frank Weber -- Elizabeth's brother -- until 1989. Frank Weber is also the godfather of Alexa Ray.

"What, am I crazy?" Joel asks now, still a bit incredulous. "I hooked up with the Borgias! What a family to pick! "

Responds Weber's attorney, Patrick Monaghan: "Anyone who can read Joel's depositions will see how lame his case truly is. He's been involved in disputes with virtually everyone who's ever managed him, and we think his claims are totally without merit... .

"Joel renewed Weber's management agreement several times and was represented by able and competent counsel each time," says Monaghan. "He's going to lose, and he's going to lose big." Joel's suit -- seeking $90 million in damages -- is expected to go to trial early next year; Weber, meanwhile, has filed a counterclaim for $11 million in damages.

Joel accepts some of the blame for this legal morass: Even after his divorce from Elizabeth Weber, he never really paid attention to the business end of things. "I stayed away from it on purpose, as if it would compromise my 'artistry.' For a long time, I was overly sensitive to this accusation that I was a hitmaker-meister just grinding it out for the money. So I proved I wasn't doing it for the money because I didn't know nothing about my money -- and that way I'd know that I had 'integrity.'

"I shoulda looked out for the money," he concludes.

Joel has been giving master classes at various colleges and conservatories -- "I know when I was starting out, I wish I could have knocked on Bob Dylan's door and asked him a few questions, or had a chance to talk to the Beatles" -- and it's hardly surprising that along with advice on songwriting, he suggests taking an accounting course. "And it doesn't hurt to know a little law, either. I've been asked: 'How can someone so skilled at making music be so stupid about business?' My answer is: 'How can so many people skilled at business be so ignorant about music?' "

Okay, he's a little touchy.

"Maybe it has to do with middle age," Joel says. No, not the touchiness -- the new outlook.

"When one turns 40, one starts to take inventory," Joel suggests. "It's time to take stock of things, which means a certain amount of dwelling on one's self. I enjoy having a child because until you have children, the center of attention in your world is yourself. Then you have a child and {the attention} immediately goes to the child, which is very healthy. Enough already -- 35 years of me! It changes everything, and it changed my perception of a lot of other things."

Joel says he once dreaded getting older. "I thought it meant you were sedentary in your ways, set in your ideas, stiff. But I've found I'm taking on more new ideas at this age than I had when I was younger, when I was very stubborn. Now I like to argue and debate -- maybe that's the Talmudic Jew in me. In the old days, I could not be moved; now I'm wide open and I find that reflected in my music. It's a very rich, spiritual time of life."

In the title track of "River of Dreams," Joel sings: "From the mountains of faith to a river so deep/ I must be looking for something/ something sacred I lost." That something, he explains, was a matter of faith, not to be confused with a matter of trust.

"There is a difference," he says. "Trust is something you give, something that comes out of you, something that can be broken. Faith is something that you have that is not necessarily given, something that is sustaining. You can have your trust betrayed and still not lose faith.

"I realized I had to regain the faith; I had to have it reaffirmed somehow," Joel explains. "So I found things that were substantial and sustaining and worth believing that were right there around me."

Not surprisingly, this included his 10-year marriage to Christie Brinkley. The giddiness of "Uptown Girl," written when Joel was first dating Brinkley, has evolved to "All About Soul," with its suggestion that "underneath the love is a stronger emotion." "Sometimes love gets pretty thinly stretched," Joel explains. "What sustains that? It's soul... .

"How do you write a deeply felt love song celebrating a woman without it being trite, or hackneyed? It's so difficult," Joel admits. "But it's something we feel, something that matures in a relationship. That subject hasn't really been dealt with: married love, people who've been together for a long time. There's always infatuation songs and lust songs, but who writes about abiding love? If the baby boom did in fact create this gigantic form of music and wants to bring it with them through life, then it does have to change and deal with more mature topics."

The Joel-Brinkley celebrity marriage has had its share of doubters -- beauty-and-the-beast jokes are not uncommon -- but the two seem to have weathered them well.

"When we're seen together, it's almost part of the job," Joel concedes. "We know we're going to get photographed. How much of that do you want to let hang you up? When we're home, we're just like any other married couple, and the superstar-supermodel thing goes right out the window. We talk about who's going to give Alexa Ray a bath tonight ... who's going to take out the garbage ... are you cooking, am I cooking, then you've got to clean the table. That's really how we are. That's the reality, not what you read about. It's good to have a sense of humor."

Joel cites a favorite story that appeared in one of the tabloids recently. "It said I had been cruelly goading Christie about her looks, saying that she's no spring chicken anymore, and I intimidated her so much that she went and got plastic surgery. Think about it: Who in this family needs plastic surgery?"

Brinkley, a onetime art student, did the painting on the cover of "River of Dreams." Joel points out that she was studying art in Paris when some prescient photographer snapped her walking down the street. Brinkley ended up on the cover of a fashion magazine the first time she was professionally photographed, and it soon changed her career path.

Joel's own art endeavors are decidedly more circumscribed. "I just draw boats, which I've been obsessed with since I was a little kid," he says. "I used to 'borrow' boats. Not steal -- I'd always get them back."

Now he doesn't have to: that's Brinkley's rendering of Joel's 36-foot lobster boat, the Alexa, on the "River of Dreams" cover. When Joel goes off to his office-studio in nearby Montauk, he must kiss Alexa goodbye, but she often comes along on tour. (Not the boat, the daughter.)

"In concert, she likes certain songs a lot -- she thinks they're her songs -- and when the crowd sings along, she gets a kick out of that. She sees the fact that everybody's enjoying themselves, so she thinks it's a good job.

"But she also sees the toll it takes physically and emotionally," says Joel. "It's draining -- sometimes I come home and just lay there like a vegetable, and she says, 'You work too hard, Daddy.' It was easier when I was younger."

Joel says the next 18 months constitute his last extended tour. "This is the last time I'm going to do these long, drawn-out hitches in the Army. Here I am 44 -- when am I going to have the physical wherewithal, or the desire, to really spend that much time out on the road anymore? I've got a little girl, I'm happily married, I love my home, I've seen the world, hotels don't thrill me anymore, so I might as well do it now, one big last long tour. It doesn't mean I'm not going to perform any more. It means I've got to figure out how I'm going to perform... ."

The entertainer, it seems, is no longer under pressure. And he's even found a manager he trusts.

"He's much better than any of the other managers," Joel says. "I have a very good simpatico with this guy. My schedule is more humane, because he knows that a recovery day is as important as a workday. I don't want to go on stage drained, tired, regretting it. He's also set up breaks so {band members} can go home to their families."

The new manager's name? Billy Joel.