Some people believe that saliva has an anti viral effect. If someone has HIV, there is probably a little less chance of getting it through oral compared to other ways, but the chance is still there. The concentration of HIV is probably a little less in vaginal secretions than in semen. If you have infections or abrasions in your mouth, then there is a risk. My girlfriend recently told me I climax too fast for her liking, and I really want to satisfy her.
Men normally climax quickly unless they train themselves to extend themselves.
To last longer you need to have your partner bring you close to orgasm and then stop for a minute and begin again. If you do this often, then you will learn how to make yourself last longer. I usually ask people to hold off on intercourse and do it manually. Then after 2-3 weeks start with intercourse again. Most women really regard the penis as unsanitary.