if you really want to make short work of it, use a grinder with a 36 paper to remove paint from the metal surfaces.
using chemical is messy and not environmentally friendly, but some prefer this method.
yes, a 36 paper is harsh, it will leave scratches that must be filled with a good filler primer and lots of block sanding. However, if your car has multiple paint layers (mine had 12 coats of paint), the 36 paper is the way to go. be very gentle on the aluminum pcs (hood, front fenders, doors, sunroof)....as they will warp easily.
you can check with paint suppliers to see if there is a chemical paint remover for the poly bumper covers (I hear that there is), but again, be careful. Sanding these pcs may be the better way to go.
Dad did his (below) totally by hand.....no chemicals. not bad for a 25 foot paint job, as he had less than $600 in the whole deal, plus his labor.
Mine, on the other hand, may never get done......maybe the teenager will get motivated and finish it.
--R