Besides a well ventilated area and a few hours spare, you'll need:
If it comes unpainted or partially, yes. Well, that's if you don't want to drive around with a see-through body shell.
Most body shells come unpainted (clear), some come pre-painted and some even come partially painted (like the Traxxas ProGraphix range).
The body shell should have either painted or unpainted in it's name. Note: don't rely on the image as some manufactures paint the body just for the image, as it's easier to see.