Actually the good thing about the air ratchets is that you loosen and tighten by hand. You can then "feel" how tight you are getting a fastener. The air is to "run" the fastener.

If you want to just bust something loose and run it, you need a 3/8" butterfly or a 1/2" pistol grip.

A good combination to have would be a 1/2" pistol grip, a 3/8" butterfly, a 3/8" air ratchet and for tight spots you can get a VERY small air ratchet that is meant for 1/4" drive but has a 3/8" ratchet mechanism from Sears. I'm sure that others make one, but I have only seen it at Sears. This little darlin' is great for getting in really tight spots for running fasteners. The same one in 1/4" drive might be handy from time to time.

Get pigtail hoses with a swivel connection for each air tool and keep a can of marvel mystery oil handy. Put a couple of drops in each tool before you use it each day.

A 5HP, 30 gallon will be plenty for your purposes, but it will require 220V.

Enjoy,