Well, first mission, haven't even gotten to the bunker yet and I think I may need to restart. See, I killed a raider right in front of a door, and I need to open that door. When I go to open it, it says "Blocked". Is there any way to make a body disappear, or am I screwed?

I don't know which door....maybe the real first one? The one with bars?
Anyway, its unlike that you are stuck because the dead body blocks your path.
You will either need the right key, or you must search the area because there
is a second way in. In the first mission you must travel around the entire complex
till you reach your target. And remember to save because we don't want to hurt
the tribesman.