The Dallas Theater Center, an oasis in this vibrant, sometimes vulgar city, is unique on two counts:

Its home is the only theater -- and the final building - designed by Frank Lloyd Wright; and it differs from other regional theaters in that its performers are also active staff teachers designers, craftsmen, writers, directors and administrators - all nonunion. The result is a striking atmosphere of mutual respect and concern.

As with all theaters, a single personality has been its driving force: Paul Baker, on of whose recent innovations, "Playmarket, drew producers, agents and writers from around the land to the third of its biennial series last month.

Now in his mid-60s, Baker has been as courageous an innovator as Arena Stage's Zelda Fichandler. He opened his Kalita Humphreys Theater just 20 years ago, but it was not until 1962 that the present, permanent company began.

He has attracted such names as Charles Laughton, Zero Mostel and Burgess Meredith as guest artists and introduced such novelties as Hamlet performed by three actors.

Baker's home, about a 10-minute drive from the Turtle Creek building, embodies two lives of Dallas Theater Center. A deep, wide, well-tended lawn leads to a home which could be the backdrop of one of those TV commercials indicating ideal American family life. The house proves larger, more adventurous than appears from outside.

Paintings and handcrafts quicken the large, essentially simple rooms. A post-theater crowd is forming, some headed for the heaped buffet table in the large dining room, others to a bar just off the trim back garden. On one wall, off a back staircase, hangs a Confederate flag.

"Know where I got that?" asks our host. "Arena Stage gave it to me after the closing of "The Last Meeting of the Knights of the White Magnolia.' "

The speaker is Preston Jones, known to the rest of the country as author of "A Texas Trilogy," but longer known here as an actor, whose most recent role was as the perceptive sheriff in the previous night's new play, "Firekeeper." Its author is Mark Medoff, who wrote the award-winning "When You Comin' Back, Red Ryder" and who also is chairman of the drama department of New Mexico State University. Another Jones role was the part Paul Muni created in "Inherit the Wind," whose co-author, Jerome Lawrence, is talking with Medoff. Across the room is a youthful actree-turned-playwright, Mary, Rohde, whose "Lady Bug, Lady Bug, Fly Away Home" is the most generally admired of the nine new "Playmarket" offerings.

The hostess is tall, lean, dark and has a sphinx - likeface Mary Sue Preston, actress (Schiller's Elizabeth, "street-car's" Blanch, O'Neill's Mary Tyrone and "The Seagull's" Irina), designer ("Marat/Sade," "the Caucasian Chalk Circle," "Macbeth"), director ("The Importance of Being Earnest," "Summer and Smoke" and yesterday's "Doors"), professor of drama and, since its founding, assistant director of Dallas Theater Center, where husband Preston's plays would be introduced.

"I'm more guest than hostess," says Mary Sue. "Our hospitality committee has volunteered to clean up after the party; and I know that before the morning matinee, everything here will be cleaned up and in order."

"You see now" remarks Preston, "why the New York fate of 'Trilogy' didn't mean all that much to us. 'Knights', 'Lu Ann' and 'Graduate' are now being acted all over the country abroad too, and we have this sane, busy life in the theater here. I've kept writing plays and both of us acting and we find time for recreation, hunting, fishing, too. Couldn't begin to live this way on the New York-Hollywood line."

At the theater, the newest Jones script is one of the nine "Playmarket" offerings, "Remember." Here Jones tackles a subject no playwright so far has examined, the effect on ordinary people of current reforms in this Roman Catholic Church.

In "Remember," Adrian, a not-very-successful middle-aged actor, has returned to appear at a dinner theater in the town where he was raised. When George, a boyhood friend, drops by, Adrian is glad to be rid of Rosalee, his roomie, a lanky, outspoken lass who ranks only as property mistress and general understudy. Adrian and George had the same religious training in their Catholic school and Rosalee is hardly appropriate.

A more unexpected arrival is the older Dan, a breezy real-estate man but, when the boys were boys, a respected priest and strict disciplinarian. Not only is the former teaching brother married, he also has made a pass at Rosalee and outspokenly questions his years in the priesthood - which perplexes his still-struggling students.

A fresh, dramatic idea, and once Jones gets through his rather lengthy preliminaries, sharp, questioning conflicts result. Was it George, as Adrian thinks, or was it Adrian, as George accuses, who dreamed up "Frankology"? This is an imaginary, parallel religion to Christianity, promulgated by the imagined elder brother of Jesus, Frank. It's a brilliant, humorous interlude in no way debasing catholicism. Jones' criticism is rooted in how man has perverted Christianity and how confused its believers have become. His dialogue is wonderfully concise and sayable and he has been resourceful with plot turns. The script is still in progress.

Mary Rohde had done a score of roles at the Dallas Theater Center, took off for two New York years and returned to leads in "The Three Sisters" and "Vanities." Her experience with new plays and limited female roles inspired her to try playwriting, with "Lady Bug" the result, another example that actors understand the trick of dialogue writing better than most other writers.

Rohde centers on an aging beautyshop owner in a small town whose son and daughter have had their marital scrapes. Mama, dashingly acted by Cheryl Denson, is a richly observed character of raw, defiant optimism who somehow will ease along the life of her pregnant, unmarried grand-daughter. The characters are individualized but never caricatured and the play could be relished everywhere, though probably not on Broadway, where ordinary folk are not welcome on stages.

Whatever happens for Rohde's play, she has now obtained what is most valuable for the new playwright: "representation.." International Creative Management's Bridget Aschenberg admired "Lady Bug" and signed Rohde as a client.

Medoff has long had representation. "Ryder" and "The Wager both have won honors, reproductions and reprints. In "Firekeeper," set in New Mexico of 50 years ago, he writes of a priest, his troubled parsionioners and a sheriff who attempts to create order in a chaotic situation.

This is a shift in Medoff's approach, a far deeper play than he has previously conceived, with its owner deliberate pace and viewpoint. With a good deal of incident, even melodramatics, Medoff tells us, I suspect, too much. Like other current playwrights, Medoff uses old movies as a kind of mood shorthand. His troubled priest once wanted to be a second Buster Keaton and Medoff uses silent screen subtitles to suggest Father Pascal's thoughts, a device which gets in the way of his complex story line. John Figlmiller is admirably passionate in the part but without the movie images, "Firekeeper" would be a more satisfying play.

Some half-dozen other scripts reflect particular interests of the community-minded company, a children's play by young Paul Munger, "The Squires and the Golden Kings," a mime creation, "Interweave," by John R. Stevens and Robin Flatt.

The least impressive, indeed most depressing, has been one of the season's box officer hits: "Blood Money," a musical by M.G. Johnston to a score by Jim Abbot. It imagines Vera, a scientist, assigned to create heroes for a heroless present. She schemes to steal the dreams of three free spirits of the American past, Jesse James, Walt Whitman and Neal Cassady, Jack Kerouac's buddy. A villain is introduced in the form of a goose-stepping Nazi whom Johnston calls Rudolf Hess.

Since Hess was not quite the buffoon portrayed and since both James and Cassady are hardly true American heroes, even dreamers, the result is misleading, a chaotic mess. Its choice as a fairly elaborate production is mystifying. CAPTION: Pictures 1, 2 and 3, In Dallas, clockwise from top left: The Kalita Humphreys Theater, Cheryl Denson and Micheal Scudday in "Ladybug,Ladybug, Fly Away Home" and John Figlmiller (left) and Ryland Merkey in "Remember." by Linda Blase