z32 caliper checking

[bcar240]

I just got some used z32 front calipers and I just wanted to check them over to make sure they were working ok before I put them on (specifically wanna check for stuck pistons). Any good ways to do that?

Also, one of them didn't have that thin metal piece on the top, not sure of the exact name, see the attached pic. This looks like an important piece, lol. Also, I am kinda a brake newb, so do I have to do anything special to shim them for new pads or are the shims already on there ok for any pads? I have seen the 300zx brake swaps sites and stuff, so I think it will go ok. Any advice is welcome, , the day I do the swap will be a long one. Thanks!