Just be careful you, need to move the toffee wheel about or else it will heat and burn the paint. If youve never used one before have a practice on something else.
While the PU is still wet, you can remove it with acetone, panel wipe, etc.
The big caution is that although that'll work fine on old factory paint or 2pac, the solvent will tend to remove rattle can paint.
Body shops will generally glue panels on and then paint, but this can cause real issues is the paint doesn't quite match and if you're not very skilled.