Q. Have sisters Vanessa and Lynn Redgrave declined to act together because they are so competitive?

A. After more than a quarter-century of individual successes, the Redgraves recently got together for the ABC remake of the memorable chiller "Whatever Happened to Baby Jane?" Vanessa, the exotic extremist, and Lynn, the earth mother, even pursued their careers on different continents - Vanessa at home in Britain and Lynn in the United States. "I think when we were first acting, we thought it would be a gimmick to appear together," Lynn says. As the child of an acting family, Lynn - six years younger than Vanessa, who is 53 - also wanted to preserve her own identity. Nonetheless, they are close. "This movie (in which Lynn is Baby Jane) is the longest we've been together on a day-to-day basis since Vanessa left home when she was 20," she says. "We've had great fun talking and giggling over tea."Q. About a year ago, I saw a movie on TV called "The Barretts of Wimpole Street" about Elizabeth Barrett and Robert Browning. It was a very old movie. Who were the lead actor and actress? - K.D., Marlton, N.J.

A. Norma Shearer and Fredric March were the lovers in the 1934 movie. The director, Sidney Franklin, did a second version in 1957 with Jennifer Jones and Bill Travers. Critics think the earlier movie is the best. Neither is on tape.

Q. Tell me about the actor who plays Miles on "Murphy Brown." How old is he? Married? Where can I write the cast of "Murphy Brown"? - M.C., Plymouth, Mich.

A. Grant Shaud was born Oct. 17 (he won't tell the year but he's in his late 20s) in Evanston, Ill., and was raised in Philadelphia. He studied journalism at the University of Richmond but decided to be an actor. Five months after he went to New York, he was cast in the play "Torch Song Trilogy." He did more plays before moving to Los Angeles. He's single. Write: Warner Bros. Television, 4000 Warner Blvd., Burbank, Calif. 91522.

Q. I really enjoy "Uncle Buck," especially the beautiful young lady Dah-ve Chodan who plays Tia. Give some personal facts. - J.P., East Haven, Conn.

A. Chodan was born Nov. 9, 1974, in Alta Loma, Calif. She was 6 when she did a suntan lotion commercial. She's been working ever since on TV in "The Wonder Years," "Out of This World," "Punky Brewster," "Emerald Point N.A.S." and the TV movie "Cast the First Stone." She's been in the feature films "Defense Play," "Armed Response" and "Hot Pursuit."

Q. Is Michelle Phillips, who is one of the stars of "Knots Landing," the same Michelle Phillips of the singing group Mamas and Papas? - J.C., Willow Grove, Pa.

A. She is. Phillips made her acting debut in 1973's "Dillinger" playing a part-native American. She says she got the role by telling the director that she was half Cherokee. Her other features include "Let It Ride," "Valentino," "Bloodline" and "The Man with Bogart's Face." On TV she's done "Aspen," "Trenchcoat in Paradise" and had a recurring role in "Hotel." Meantime, daughter Chynna carries on the musical tradition of her parents, John Phillips and Michelle. She's part of the group Wilson Phillips along with the daughters of Beach Boy Brian Wilson.

Q. I'd like to congratulate Fox on their great new show "Beverly Hills 90210." Give me some information on Shannen Doherty. - P.C., Irvine, Calif.

A. Doherty was born April 12, 1971, in Memphis, Tenn., and made her acting bow at 10 in "Father Murphy." She was Jenny Wilder in "Little House: A New Beginning" and Kriss Witherspoon in "Our House." She's done a string of TV guest roles, too, and the TV movie "The Other Love" and miniseries "Robert Kennedy and His Times."

Q. "Yancy Derringer," a 1950s western, was my favorite. Who starred and who played his Indian sidekick? - M.G.F., Flint, Mich.

A. Jock Mahoney was Derringer; X. Brands was his pal. It wasn't a western. It was set in post-Civil War New Orleans and Derringer was a crime fighter. It ran 1958-59.

Q. I recently saw Rose Marie on "Murphy Brown." She was instantly recognizable from the bow in her hair. On what series did she have a regular part and what character did she play? - R.H., Philadelphia.

A. Rose Marie did three series; "My Sister Eileen," 1960-61, and "The Doris Day Show," 1969-71, are two, but the one in the middle, "The Dick Van Dyke Show," 1961-66, is the one people remember. She played wise-cracking comedy writer Sally Rogers. It made her a star all over again. As a youngster, "Baby Rose Marie" was a hit on radio with her own network show.

Q. I've watched the Johnny Carson show since the beginning. Where can I write him? - T.A.G., Dearborn Heights, Mich.

A. NBC-TV, 3000 W. Alameda Ave., Burbank, Calif. 91523.

Q. What was the name of the TV movie in which Paul Sorvino played a deaf lawyer defending a deaf black boy? Will it ever be shown again? I think it was one of his best acting jobs. - S.D., Lakeland, Fla.

A. "Dummy," the 1979 movie, co-starred LaVar Burton as the young deaf-mute defended by Sorvino, as a deaf lawyer. The movie was based on a true case in Illinois.

Q. Give me the following info on my favorite game show host, Bob Barker: real name, birthdate, marital status. - N.B., Wichita Falls, Texas.

A. Barker uses his real name. He was born Dec. 12, 1923, in Darrington, Wash. He is a widower.

Q. How do I write the person who produces or writes "Generations," a very different and interesting show? Who plays Sam, Kyle, Maya, Ruth Marshall? - Ladies of Denver, Colo.

A. Kelly Rutherford is Sam Whitmore, Robert Sorti is Lt. Kyle Masters, Vivica A. Fox is Maya and Joan Pringle is Ruth Marshall. Sally Sussman, who created the soap, is executive producer and head writer. Write: NBC-TV, 3000 W. Alameda Ave., Burbank, Calif. 91523. Your letter may soothe her feelings. NBC has announced that "Generations" will leave the air Jan. 25. Poor ratings, partly because so many NBC station refused to carry the soap, is the reason.

Q. Did Jonelle Allen, who plays Doreen on "Generations," ever win a Tony Award? - C.F., Glendale, Calif.

A. Allen had a Tony nomination for "Two Gentlemen of Verona" but didn't win. She did pick up a shelf full of other awards for her work in the play: The Drama Critics Award, the Drama Desk, the Outer Circle Award and the Theater World Award. She's a veteran stage performer, starting at age 5 in "The Wisteria Trees" with Helen Hayes.

Q. Is Anne Archer the daughter of show business parents? I've been trying to find out since I saw "Fatal Attraction." - A.P., Chicago.

A. Archer is the daughter of Marjorie Lord, best known as Danny Thomas' TV wife, and her first husband, actor John Archer.

Q. My brothers and I get into big arguments over the age of Johnny Cash. Settle this please. - Mrs. K.F., Ann Arbor, Mich.

A. Cash was born Feb. 26, 1932.

Q. Give me some stats on Richard Gere of "Pretty Woman." - M.S., Pueblo, Colo.

A. Gere is 41. Born Aug. 31, 1949, in Philadelphia, he grew up in Syracuse, N.Y., attended the University of Massachusetts for two years, started in summer stock in 1967, got his big break replacing Barry Bostwick as Danny Zuko in the Broadway company of "Grease," and made his movie debut in "Report to the Commissioner" in 1975. "American Gigolo" in 1980 made him a star. He's single.

Q. What's happened to the beautiful British actress Jenny Agutter? I hope she's still acting. - G.W.S., Biloxi, Miss.

A. She is. In fact, you can see her in "Child's Play 2," currently in theaters. Agutter, 41, works on both sides of the Atlantic .