What do these people have in common: Anthony Michael Hall, Randy Quaid, Robert Downey, Nora Dunn, Joan Cusack, Danitra Vance, Terry Sweeney and John Lovitz? For one thing, they are all members of the new repertory company of NBC's once-more-revised "Saturday Night Live."

For another, they are all young. Oh, are they young! Like, young -- as in "er than Springtime." Hall, who starred in the films "Sixteen Candles" and "The Breakfast Club," and whom everyone calls "Michael," is, at 17 years old, the youngest. The average age of the new cast is 25.

Lorne Michaels, the returning producer of the show, the man who captained it for its first five golden years, starting in 1975, and who is now flirting with 40 himself, looks at his new troupers as they romp and wriggle through a group photo session in a vast and artsily spartan SoHo loft and contemplates their youth. "I think," he says, "it's terrifying."

The cast will be officially presented to the press this Saturday. On Nov. 9, they will face the live cameras of NBC's Studio 8H for the first time as an ensemble. "Saturday Night Live," which NBC Entertainment President Brandon Tartikoff came that close to canceling before Michaels agreed to return, is back for a reprieve, and it's up to Michaels to restore to it the kind of ratings glory it once enjoyed and also to traverse the generation gap between his gray-haired self and the cast he has selected.

"Michael Hall was 7 when 'Saturday Night Live' came on," Michaels notes. "They all watched the show as kids. They just take it as what television was like. They don't know there was a period before that."

Among the guest hosts scheduled for the season are "SNL" veteran Chevy Chase (the second show, Nov. 16), the inimitable Arnold Schwarzenegger and, tentatively set for the first show, one of the biggest stars in the universe, Madonna. Martin Short, a member of last season's regular cast, did not want to return on a weekly basis, but is set to be a guest host. Michaels was not interested in getting any of the other recent cast members to return, including Billy Crystal. According to industry rumor, Crystal was getting $30,000 per show, which Michaels says he could not afford (the original cast members in 1975 were paid $500 a week).

Michaels also indicates he is not particularly eager to have as guest hosts Ted Turner or Bob Guccione Sr. and Jr., although he says representatives of both these camps have expressed interest in appearing. The guy Michaels would really like to get is Richard Nixon, but he's not holding his breath on that one. Even in the old days, he recalls, he always wanted to get Orson Welles, but was repeatedly told "no" by Welles' associates, "and the reason given was always that it wasn't enough money." The day after he said this, Orson Welles died.

On this particular night, after hours in "After Hours" country -- sort of on the line between Little Italy and Little Vietnam -- the cast has been gathered so that photographer and graphic artist Edie Baskin (as in Baskin-Robbins, though she balks at being called "the ice cream heiress") can shoot them as a group. This will take, roughly speaking, all night, because after each shot everybody disbands and runs about the apartment looking for different get-ups to be gotten up in.

Hall, who always seems on the verge of hyperventilating as he buzzes the room like a tall blond bee, often gets it in his head to dash over to the record player to pick out a new tune. At one point he rushes up to a mirror and surveys his mucho moussed hair, most of which is now sticking straight up in the air, and, with a look on his face of profound disgust, sputters, "Damn, I worked on this for an hour and a half, and now look at it."

Probably the best known of the performers (although Quaid, older, also has appeared in several movies), Hall is considered one of the brightest young comic actors in films. According to his agent, who sits around watching the scene, Hall turned down the lead role in Stanley Kubrick's new movie, "Full Metal Jacket," so he could make his splash in television on this, the hippest of hip shows. "Michael is A Movie Star," the agent keeps saying with great finality. He also says Michael prefers "Saturday Night Live" over Kubrick because "he wants to have fun. This is like after school for him."

Joan Cusack appeared with Hall in "Sixteen Candles"; she was the frizzy-haired, accident-prone teen-ager with the huge neck brace, officially billed in the credits as "Geek Girl No. 1" (Hall himself was "The Geek"). She has a sweet, elfin smile, and she found out she'd made the cast only two days before the photo session. Robert Downey is the son of ever-avant-garde filmmaker Robert Downey ("Putney Swope") but prefers not to be known as Robert Downey Jr. He proved himself a sly scene stealer in films as ignoble as "Tuff Turf" and "Weird Science" (also with Hall). He says he'll be playing Mussolini's son on a forthcoming NBC mini-series and that he gets killed in a plane crash in the first episode.

Danitra Vance, the one black member of the permanent cast, will also be on the writing staff. Nora Dunn, who had been an actress part time, had to tear herself from a job as a waitress in Chicago when tapped for the show. Terry Sweeney is tall and thin and his strawberry blond hair is arranged in a daft flattop (he is wearing a bright orange sportcoat with a pair of black-and-white pants that Jackson Pollock might have painted after a rough night in a hammock). John Lovitz seems moody and mildly mysterious and midway through the photo session changes from a black leather jacket to an oversized gray sportcoat.

They all chat and dance and mug and laugh. They fondle and hug one another and make ritual trips to mirrors to check out each change of wardrobe. Michaels looks upon them with a not-quite-fatherly patience; he seems warily bemused. Told he doesn't look sufficiently worried, he says, "It's too early to be worried." There are still three whole weeks until showtime.

Al Franken, who is returning to "Saturday Night Live" with his writing partner Tom Davis, also finds the youthfulness of the cast disorienting. "Michael Hall is closer to my son's age than he is to mine," Franken says ruefully. "They come up to me and ask me stuff like, 'So, what's it like to have a baby?' " As the group reassembles for another try at a portrait, Franken stands next to a white pillar and says to himself reassuringly, "It looks like a cast." Michaels will supplement these regulars with additional "featured players."

The picture-taking continues. Someone has changed the record in the background from Talking Heads to Hall and Oates. In the back row, standing on a phone book despite a recent spurt in his own height, Michael Hall calls out, "Funk-ee! Funk-ee!" and everyone joins him in this chant to encourage funkier music. Downey, whose black hair has been slicked into a kind of punk-Jerry Lewis look, keeps yelling, "Turn it up!"

Some of the performers, though young, appear already to have attracted their own groupies.

For his cast of newcomers and tots, this is all a giggly adventure, but for Michaels, the show represents a double-edged risk. Even if it goes over like gangbusters from night one, there will be those who call his return to his old job a sheepish retreat. His 1984 try at a prime-time comedy-variety series, "The New Show," made a king-size kaboom. When he must refer to that program, he tends to refer to it mutteringly as "thenusho," so that people have to say, "The what?"

Even if they understand him perfectly, they may say "The what?" because not that many people saw it.

Earlier in the evening, Michaels was encountered back in the very same 17th-floor corner office in the RCA Building from which he ran the original "Saturday Night Live." There is a new tank of fish, but the planning board on the wall looks just as it did back then. "It is eerie to be back on the 17th floor," Michaels said as he looked around the room. "At first I thought it would be like going back to high school and finding that all the drinking fountains are too low. But this is different."

The first time he showed up to reclaim the office, former "SNL" producer Dick Ebersol was still sitting at the old wooden desk inside. Michaels was cautioned at the door by a secretary. He waited outside until Ebersol had left. Ebersol now produces the "Saturday Night Main Event" wrestling specials and next year will produce the Emmy Awards telecast for prime time. He's not known as a creative genius, to be kind about it, but on the other hand, he did rescue "SNL" from the complete disaster of its sixth season (under another producer) and got it back in working order.

Prospects for this 11th season of "Saturday Night" look promising. Although most of the cast are unseen by the national audience, many look possessed of a certain appealingly brash devilishness, and Hall darts around with the intimidating energy of an F14. The new set will be a stylized replica of 42nd Street -- not the subway station for a change, the actual above-ground street.

At every corner, Michaels is being reminded that things have changed. The budget for the first season of "Saturday Night Live" was around $200,000 per show; this season it will be $765,000 (actually down from last year's $800,000). Another change Michaels has noted is that network censors are fanatically adamant that there be no mention of drugs in the scripts. This rigid edict filters down from NBC Chairman Grant Tinker. And Michaels is not worried that his new cast will suffer the personal drug problems of the old; he says they tend to think of drugs as something old folks do. Or did.

During the umpteenth lull between picture takings, as the cast meanders off to ransack the bedrooms for more clothes and hit the mousse cans again, Baskin saunters over to Michaels and Franken with two 8-by-10 photographs in her hand. "Original cast pictures!" she beams, holding out shots she took a decade ago of John Belushi, Dan Aykroyd, Gilda Radner, Jane Curtin, Laraine Newman and Garrett Morris (Chevy was absent because he was not under contract like the other Not Ready for Prime Time Players).

Michaels looks at the photos with a sentimental smile. Franken does, too, the way he might regard an old yearbook picture. Now the new cast members are gathering around and staring down at the photographs as if they had been unearthed at an archeological dig. Suddenly they are reminded of the footsteps in which they are following, and for just a moment, the prevailing mood of sassy pandemonium gives way to a jolt of rapt reverence. Live, from New York, they seem fleetingly to realize, it's the eve of the dawn of a new Saturday night.