Petite, blonde—"ordinary" is her description—Kay Warren has for 32 years played the role of nurturer, best friend and helpmeet. But for the past year Kay has been on the lecture circuit herself, preaching that Christians ought to apply themselves to the problem of AIDS, even though it raises uncomfortable questions about sex. This week her memoir, "Dangerous Surrender," comes out, and now Kay Warren has emerged at the center of things.