So listen, I get it. I need numbers. I'm no engineer or anything, but I need to know what I'm facing, or someone I love is facing.
However, with STDs, it's almost impossible to know. There are so many variables even for kissing - how long did you kiss, were symptoms present, was it an open mouth kiss. With sex, even more so - was a condom used, how long did it last, how often are condoms used by both partners, age (different age groups have different risks for things, like chlamydia is far more common in younger people than older), gender of partners, your gender, etc.
I'm also no doctor, but I wouldn't worry about oral HPV. It's not that common, and there are more likely scenarios.
Oral herpes is one. Like GuitarRox stated, up to 80% of the population has it (it goes up as you get older). Without a sore present, I would kiss someone with it. I am quite sure that I have. If you've kissed more than a few people, I'm quite sure you have, too. If you want to know if you already have it, ask your doctor for a type specific IgG blood test.
Chlamydia, in theory, can live in the throat, but many experts swear they've never seen it.
I wouldn't worry about kissing and oral gonorrhea. If I were a man, and someone had oral gonorrhea, I'd refuse oral sex from that person, but kissing is fine.
If someone has a syphilis sore on/in their mouth, I would turn the kiss down. I don't care how hot he/she is. Syphilis isn't that common, either, so in the absence of sores, I wouldn't worry about it.
Kissing is overall pretty safe. You have a better chance of getting a cold, the flu, strep, mono/glandular fever, etc., than an STD from it. You'll be a lot sicker with some of those than you would be with most STDs.
If you are worried about catching oral herpes, kiss women you know or run the risk. But 80 percent of the general population have herpes simplex one and many got it as children. If there are no visible lesions, there is only a small risk of transmission.
Doctors take a code of ethics that unfortunately the general public doesn't seem to try to live up to. Most successful men have a lot of women throw themselves at them and are used to saying no especially when they could lose their license to practice medicine over it.
Ask a relevant question on std's and we'll try to help.