If I immediately shower after getting rimmed do you think that would decrease my chances of getting herpes, or possibly any other std's?
No, it really won't. But as long as the person rimming you doesn't have any cold sores on their lips, I wouldn't be too concerned about HSV. Another possible risk would be syphillis if the person has a chancre on their tongue. Really they are the ones putting themselves at risk for Hep A and other parasites because they are the ones doing the rimming. Your risk of STI's from being rimmed are extremely low.
i DO think it would decrease the risk, but it would NOT eliminate the risk.
The herpes virus takes up to an hour to invade it's host cell, so soaps and alcohols are a good tool to prevent infection after exposure. Really though, I wouldn't take the chance and would stay away from oral sex with anyone with coldsores.