1. is it good to use saliva or any lubricant for sex? 2. is it good to lick vagina?

It would be better to use a water-based lubricant like K-Y Jelly. You may lick the vulva, the face. Vagina is the hole. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines

Generally, if a lubricant is needed for sex, it is best to use a water-based lubricant. Cunnilingus (licking the vulva and vagina), in the absence of any sexually transmitted diseases, will not cause any harm. Be safe in your sexual practices. Good luck.