1. HD Loader/advance will reformat the drive for the PS2....
2. any drive that fits should work (even drives that don't fit can be made to fit).... although it is suggested to have a large drive... because the average game is 2 - 4GB in size.... But if you are using a Pressed disc of HD Loader/HDA you can't access anymore than the first 137GB of data... but a patched version can read a drive up to 2TB.
3. You can use FAPLink to send games to the PS2 over a network from your PC.. or use Winhiip to install directly from PC to PS2 HDD... you would be better using FAPLink and Winhiip
4. Not natively.... you can transfer gamesave to the HDD with MC Manager... but games can not save to or read from the HDD....
It's all good... that's how I learned.. and using the search function every 3 sec... to find more info on these programs i suggest using the search function...
PS3 Slim 320GB
PS2 v11 exploit w/300GB Maxtor
PS2 v10 exploit w/80GB Samsung - Network Games
PS2 v10 exploit w/60GB Samsung - Network Games
PSP 1001 3.52M33 w/10GB total storage
NDS DSReal 4GB