No, same sex kissing in public doesn't bother me. The "heavier" the petting gets, the more I wish they would just get a room.
As for AIDS, Eug is 100% correct. Male homesexual activities tend to be riskier for several reasons that increases the chances of them becoming infected, but heterosexuals are at risk as well.
Male homosexuals are more at risk because they tend to be more promiscuous and because anal sex is a very common style of sex for them. During most anal sex, there almost always is some tearing of tissues and that makes for a more direct route into the bloodstream for the virus. Oral and vaginal sex are less risky, but unprotected sex of any kind is a risk.
Sharing of needles is still a huge way for the virus to spread as well.
My wife's an MD and she has been pricked twice while caring for patients. Then the waiting for the AIDS test to come home becomes nerve-racking. Before I was married, I used to get myself tested once a year or so. I was being carefull but not abstaining so I made the decision to decrease the chance of me spreading it should my behaviour make me into a risk. Considering my age (34) and the period in which I was being tested, the risk was fairly small. Canada (and Montreal, where I grew up) made a big effort early on to spread AIDS awareness and UI'm sure it saved many people's lives (and cut down on unwanted pregnancies, although I've never looked up the stats to be sure on that).
Michael