Identifying drive series and compatible donors

So I got a whole bunch of Seagate Momentus drives from a previous job and I want to use them to learn how to do head swaps, etc. They aren't the same models but are all 2.5" drives. I have been reading some articles on doing head swaps, and I know I need to match the head map and number of platters.

I'm getting confused about how to determine the number of heads and platters, whether they have an internal or external load/unload ramp, and the drive series so I can buy the proper head removal tools (HDDSurgery lists many different types).

I do know not too move the platters without the heads off and of course to use a clean room, which will be no problem. But can anyone give any advice on just getting started with these (stupid) questions?

Thanks!