If the OP is circumcised, then the odds of him catching AIDS are lower. But the odds of him giving the bottom aids are the same. (aka, the ass has same odds of receiving the HIV virus from sperm whether the penetrator is cut or uncut).
When you get tested, there is no reason for you to tell them what sexual antic you were up to.
A one time experimentation with another guy makes you bi at best. Not gay. So don't worry about this experiment making you gay. At the end of the day, we all have sexual urges, and if one day, you wanted to try this, you tried it. There is nothing wrong with it.