I'm no expert, but here's my opinon anyway:
Pan baffles
Yes the oil will sorta "waterfall" down, but not anywhere near the volume that it will climb the pan.
Windage trays
Both types work. I've never really liked the screen ones just because they look cheap. With either, the oil returns to the pan plenty quick.
Crank scrapers
Don't put one on the driver's side for the reason you described, just on the passenger side. The idea is to keep the oil in the pan.
Now for the real question. Does any of this really do any good?
IMO, it depends on what you're expecting. Chevy oiling systems are very good from the factory, so, unless you really wind your engine to the moon, you won't significantly improve it. Anything you can do to keep oil in the pan to be used for lubrication, is good. Just don't expect your car to be quicker or faster.
I'm sure on a dyno, an engine will make more power by controlling windage, but not enough to show any real improvement on the track.
An exception to this might be an engine that sees very high rpm....