NO
Only if you want to play online with other people otherwise theres a single player with A.I
No. You must buy it and install it on a computer, preferably with a working internet connection, to play on the PC.
4 players can play in Left 4 Dead 2.
Short answer: Yes, of course. Technical answer: The operating system in itself, can play Left 4 Dead 2. But to play Left 4 Dead 2 you need good enough parts to run it. Make sure you meet the system specifications on it's steam page.
No. You can play split-screen with a friend on versus. But if you are wanting to play online, you obviously need Xbox Live.
You need to have the game either on PC or Xbox 360. From there, the menu's will guide you to online play.
No, it's compatible with Windows XP, or Vista/Vista64.
Yup, in order to play online you need internet.
Well it is rated M for mature, which is 17+ but no one really pays attension to it. If you parents allow you to play it, you can play it..
Left 4 Dead can be played on either PC or Xbox 360.
Yes, you can play left 4 dead 2 on steam if you buy from Gamestop.
Sorry to burst your bubble, but the only way to play Left 4 Dead is with Steam. Without Steam you cannot even start up the game (believe me I've tried) and so you're totally at the mercy of your school's internet. Try going to a fast food chain or a motel with free internet. Your ping will be high, but at least you can connect to Steam and play some singleplayer.