Of course, no heterosexual can be 100% sure either, unless he has been monogamous or celibate for a couple of decades. When did you have your last HIV test? Are you 100% certain that every partner you have been with has been HIV negative?
Scary stuff...
Big difference. HIV is next to impossible to transmit heterosexually (particularly F->M), which is why it is essentially unknown outside those who have sex with gay people or IV drug users (or are in these classes.)
The reason heterosexual guys don't carry HIV is that you essentially can't get it from a woman (and she won't have it unless she is a junkie or the regular partner of one.)
Your fear is overstated.
It was reported on FOX that one-third of the blood donated for the victims of the attacks was contaminated with STDs including AIDS. Anyone need a blood transfusion?