The instructions on this page are referring to playing towards the outside edge (rim) of the drum. However, the actual rim of a drum is what holds the head on, and it's usually made of metal.
Yes, absolutely correct! Of course, you will need to employ the proper striking techniques to really get the most out of those sounds, but that's the main idea of it.
HIV is one of the STIs. Having STI does not mean you have HIV. Gonorrhea, chlamydia, HPV infection, syphilis, herpes and HIV are all classified as STIs.
It's a matter of personal preference or handedness. Bongo sheet music tends to include more low notes, so your dominant hand should play the lower drum.