Are you possibly asking for help with a school task? Noone will want to help you with that, you're supposed to struggle a little! :-)
But maybe not, I'll give a few hints:
1) This is an impossible question - it's not a Linux matter it depends on the file system.
I suggest you search for something like "undelete ext3 reiserfs" etc.
2) It depends. Here's one good link: http://unix.stackexchange.com/questi...orted-in-linux