2007 subaru forester rear bumper cover

[dandydon]

My wife's subaru has rust showing between where the bumper cover meets the body over the rear wheel well
(both sides, actually.) I noticed in behind the wheel well that a fastener is there that's covered with rust but can't make out what it actually is.
The only way to truly fix it from coming back is to remove that corner (w/o taking whole cover off) and repair the rust and repaint.
Two questions: how can I remove the bumper cover in just one spot &
I have to use rattle can spray paint--can someone recommend
a brand, cost, and how much I need?