Re: Roof screw removal
I haven't tried it, but in some of the discussion threads there has been talk of using perhaps a Dremel tool to notch a stubborn Phillips head into a slotted head, and then use more muscle on a standard screw driver with to get it started.
I have two pairs of mini vise grips, one long nose and one short, that I can sometimes get to clamp around the head of a screw to provide a handle to help the screw driver move it. That's good for one or two screws, I wouldn't want to do half a bus roof that way.
I also try to tighten a stubborn screw before loosening it. I might put a Phillips screw driver in the slot, apply twisting pressure with one hand toward tightening the screw while I give the handle healthy whacks with a hammer, then twist toward loosening while I whack it again.
I also have a JC Whitney quality impact handle I can use with a hammer instead of a screwdriver, but it only has larger bits that fit the 1/2-inch drive socket adapter.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.