GOD BLESS YOU, MR ROSEWATER: book, lyrics and direction by Howard Ashman; music by Alan Menken; additional lyrics by Dennis Green; from the novel by Kurt Vonnegut; staged and choreographed by Mary Kyte; musical direction by Eric Stern; scenery by Tom Lynch, costumes by Marjorie Slaiman; lighting by Arden Fingerhut; technical director, Henry R. Gorfein; with Frederick Coffin, Robert Westernberg, Barbara Andres, Steve Liebman, Addison Powell, Robert Prosky, Stratton Walling, Terrence Currier, Theresa Rakov and Leslie Cass.

The first thing to say about "God Bless You, Mr. Rosewater" -- before the time for cold analysis ambles along -- is that this small-scale musical contains an abundance of talent, good humor and craft. The actors are enjoying themselves, and it's contagious.

If you have ever traipsed through the Kurt Vonnegut novel -- a miniature comic masterpiece, part satire, part picaresque adventure, part wishfulfillment and part graffiti pad of the author's travels across late-20th-century America -- you will be surprised to find many of its characters, fantasies and ironic insights brought to colorful life at Arena Stage, where the show opened last night. You will certainly find, in Frederick Coffin, the perfect musical-comedy incarnation of the title character, and in the book, lyrics and direction, audacity and pluck anchored by affection for the material.

The score, with music by Alan Menken and lyrics by Howard Ashman and Dennis Green, displays a penchant for meter and melody without the usual hit-driven pursuit of the universal and eternal. And there is the rare pleasure, in Arena's 360-degree surroundings of hearing songs sung at such close range that you can see the sweat on the performers' faces and -- cross my heart -- even understand the words.

Like the novel, the musical concerns the heir to an old family fortune -- a forturn assembled by a northern boy who, according to Vonnegut, heard Abe Lincoln's declaration that "no amount of money was too much to pay for the restoration of the Union," hired a substitute to fight for him, stayed home in Indiana making swords and bayonets, and "priced his merchandise in scale with the national tragedy." Two generations later, Sen. Lister Ames Rosewater, silver-haired-and-tongued Indiana Republican of the old school, sheltered his income under the umbrella of the Rosewater Foundation, with $87,472,033.61, in capital and young Eliot Rosewater at first hereditary monarch.

As we enter Eliot's life, he has leased a floor or two in a mid-Manhattan skyscraper, filled it with white modular furniture, and begun giving away money to virtually every wacko who applies. This is, of course, just what any conscience-ridden young Ivy League graduate would do in the circumstances, but Eliot's wife, father and attorneys have observed certain disturbing tendencies in the boy. He drinks. He has a peculiar fixation about volunteer firemen, whom he regards as the salt of the earth. And his mind is so thoroughly occupied with the role of oxygen in our lives that one night at the opera, during the final death-by-suffocation scene of "Aida," he bursts from his seat and shouts to the hero and heroine that they would stand a better chance of surviving if they stopped trying to sing.

The final descent into madness is Eliot's move back to the family seat in downtrodden Rosewater County, Ind. "What are you goint to do there?" his French-born wife, Sylvia, asks. And Eliot answers: "i'm going to care about these people . . . I'm going to love these discarded Americans even though they're useless and unattractive. That's going to be may work of art."

But loving the masses is a tricky business, expecially if they are useless and pathetic masses, picked clean of their self-respect and initiative by the predatory like of Eliot's ancestors. The people around Eliot can't deal with what 'e's doing. His wife lands up in a mental hospital -- a victim of "samaritrophia" or "hysterical indifference to the troubles of those less fortunate than oneself." His father accuses Eliot of having debased the word love as the Russians have debased the word democracy. And Norman Mushari, a crafty young lawyer, sees the chance to have Eliot declared insane, which would send the family fortune on to a "plain, clean, average American" cousin in Rhode Island.

Unfortunately -- from a musical-comedy standpoint -- the threat posed by Mushari comes too little too late. Adaptor Ashman has worked a great deal of matter into the first act, but neglected to include suspense in the inventory. And in a generally commendable effort to retain the discursiveness of the novel while giving more emphasis to the main characters and the main thread of the plot, he has made some questionable choices. By dropping several portraits of vital, functioning ordinary Americans, for example, he leaves us with only the sorry citizens of Rosewater to stand for the humanity Eliot wants to love. And the picture of those people -- a goofy George Price-carton world of drunks, stumblebums and junk-food addicts -- gets rather tiresome. Another debatable deletion is Sen. Rosewater's marvelous diatribe against weak-kneed liberalism, which gaves the book a complexity of moral perspective the musical lacks.

But Ashman and his collaborators have made deft additions, too. The wordplay of the patter songs (including the firemen's tribute to "the crime of arson" for saving them from "the wife and Johnny Carson") is always witty and on-the-subject. The piecemeal scenery (including a red fire truck on which the above number is performed) sweeps in from all directions with sustained ingenuity. And a second-act fantasy scene from "Pangalactic Three-Day Pass" (a fancied sci-fi novel by the fancied sci-fi writer Kilgore Trout) is rendered with a wonderful pair of extratorrestrial-looking puppets.

Above all, the show abounds with vivid and delightful performances -- more altogether, in fact, than there are performers, since almost everyone overlaps. aCoffin, as Eliot, is a floppy-haired, Teddy Roosevelt figure who puts out 100 percent from start to finish, and couldn't be more Wasp-ishly right in voice or presence. His nemesis, the lawyer Mushari, has grown about a foot in the move from book to stage, but only in order to give the role to Robert W. Westenberg, who delivers a memorably sleazy portrait of avaricious young attorneyhood. (Westenberg has a nifty song about the "magic moment" when a sum of money is about to change hands and the alert lawyer can make an undeserved share of it his own. Here as elsewhere, though, the show could use some more substantial choreography.)

Barbara Andres makes Sylvia's surrender to samaritrophia genuinely touching. Addison Powell looks so good as the senator, he could be bronzed and saddled and do honor to any of our local parks. And Steve Liebman, as cousin Fred and a slew of other characters, exhibits a conspicuous double-take to go with his conspicuous red hair and midsection.

The picture of cousin Fred and his world, however, may be one case where Ashman could have compressed more than he did. What's left from this long section of the book seems fragmentary and confusing. Besides the turnip-shaped Liebman is so evocative-looking that his mere presence just about says it all.