Concerning oral sex, can i get an STD if get semen in my mouth, or if I swallow his load?
If he has an STD, yes, it's possible, though it seems that STDs are transmitted less easily through oral than through vaginal or anal sex.
It is possible. However, if you decide to take the chance, the idea is not not have any open sores or cuts in your mouth at the time. For instance, do not brush your teeth beforehand because inevitabily you will have cut your gums. If the semen makes it past your gums, tonge and throat and into your stomach your probably ok.
Like doctorman said with the sores and cuts!
But the chances are very slim!
"...Sometimes you have to let go, just to see if there's anything worth holding on to..."