By JERRY LEWIS For GRIT “I first performed in public at the age of five, when I sang in the Methodist Church choir in Santa Ana, Calif..” Diane Keaton, star of the new comedy hit movie “Baby Boom” says. “That experience didn’t make me decide to be an actress. I didn’t decide that for another dozen years. “Even today, while I like to act, I'd rather be working behind the camera.” she says. Keaton says if she doesn’t get married soon, she'll probably adopt a child. I'd be a good mother.” she says. I'd just try to remember how my mother treated our family. When she was youn ger, she won the Mrs. Los Angeles con test and she’s still one of the most beau tiful women I’ve ever seen and one of the smartest. She went back to college at 40, and earned her degree the same year I graduated from high school.” While Diane is currently dating actor Al Pacino, they have no dates on Thurs day evenings. On that night, she pays her weekly visit as a volunteer to a home for the aged located near her New York apartment. “I sit around and talk to the guests,’ she says. “Then we turn on the music and I dance with them. One at a time. There are about 20 of them in the home, mostly women. I let them lead, and we talk while we dance. I learn things every week.” In addition to acting and directing motion pictures and MTVs, Diane has also worked at making herself a first rate photographer. Two collections of her pictures have been published under the titles Reservations and Still Life. “I think I like photography more than acting because I can do it alone. I like being alone. I hope my life never gets so complicated that I don’t do my own wis hes. Having maids and help around makes me very uncomfortable,” she says. One place where she can be alone is behind the wheel of her van, and she loves it. “If I had the chance, I'd like to drive all over the United States. Into those wonderful small towns you find in every state. I'm lucky. I can walk around any town without being recognized and mobbed. So I like to pull into a small town in Montana or Nebraska or Flori da, or anyplace, park in front of a coffee shop, go in, sit at the counter and talk to the people. You sure learn a lot about how smart the American people are, and how generous and decent they are to a stranger they never saw before. It makes you proud to be one of them.” Keaton concludes. Diane Keaton