RE: Breakdown of engine is pretty easy!?
Straight air tool oil is fine. ATF is fine. There isn't anything making one greatly better than the other. As long as you don't use WD-40. Promise you'll never use WD-40 in an engine.
Some of the engines I run have been blueprinted by engine builders. Those do not ever, ever, get taken apart unless the expert does it. Nothing will ruin a good set-up faster than an amateur taking it apart. So I don't!
Another thing I avoid is disturbing the piston/sleeve. Those parts wear into a fit, and it is runs right and starts like it should, I don't want to mess up that fit.