The prefect has called us in from play.

re your, "A disease, unchecked, will spread until it either infects such a proportion of the population that its transmission vectors are disrupted (that so many die as to prevent further transmission) or until a resistance to the disease develops, or until the behaviour of the pool-members is modified to limit the spread of the disease."

It did start off exponential. Deny that?
As you keep telling us, not all gay men put themselves at high risk.
It did indeed infect such a proportion of the (at risk) population that....      and a large number did modify their behaviour.

your number 1. Yes to all (AGAIN! how often must I tell you?!) except "the most important factor" may not be that one.

Your number 2 (No sniggering at the back!) Yes except replace "in some heterosexual populations" with "in Africa"

3. Yes. I have explained why 500% increase does not make it a very worrying amount. EXTREMELY rare and low risk for the next hundred years.

4 Yes.

5 Honestly, I don't know. Maybe.