1-in theory yes, but you wont have the ps3 case on your motherboard which contains your power and eject button...
you'll have to do some rewiring, and in my opinion not worth the time or effort
2-ps3 hdd in pc, yes but idk if it will read properly since it doesn't have the ps3 interface aka os on your pc, but im sure theres ways around it

2.1-pc hdd in ps3, " "