You won't be able to import your save game from ME1.
Mass Effect and Mass Effect 2 are both single player. There are no multiplayer modes
Yes.
This is up to you. But, my opinion is that you should definitely play ME1 first. You get a better feel on the Mass Effect Universe, and you will be more attached to the game, and will enjoy ME2 a lot more. Mass Effect 1 is a great game, as is Mass Effect 2, but if you have the time and the money, play ME1 first.
Yes. Mass effect one is available on the play station three.
No. That's a single player game.
If you don't import a save game from Mass Effect, you will automatically choose the character of the opposite gender to survive. If you play Mass Effect first, though, you can choose if you want Ashley or Kaidan to survive. So to play Mass Effect 2 as a female and with Ashley alive, you would have to play Mass Effect and let Kaidan die on Virmire.
No, the player can only play as a Human in Mass Effect 2. The player can, however, date non-humans.
Not all of them. Maybe one or two of them, but all four games will not fit on a 4 gig hard drive.
It doesn't but it does have downloadable content.
Not in the main game, however in Mass Effect 3 Multiplayer one is free to play an alien race assuming it has been unlocked
Xbox 360, PC and PlayStation 3
You do not need to own ME2 to play ME3, but if you have ME2 you can port you save into ME3, which causes choises you made in ME2 to affect the story in ME3