1. I find the pry bar type compresser to be difficult to use on the bench. I like the kind that looks like a big C clamp.
2. What you're looking for is piston to valve clearance. I set to vero lash and then back off 2-3 turns. If clearance is going to be a problem, you'll be able to see it then, before the valves actually contact the pistons. Even if turning by hand, you can damage a valve if the clearance isn't there.
3. The issue is with the hydraulic lifters. They're designed to collapse a little bit under use. When there's no
oil pressure, they will collapse a lot more, and you'll never get full valve lift.