Is there like a download to get everything from CSS without having it?
No. That's piracy.
No it's not, he wants the models, not the entire game.
Taking any part of a game is still piracy; even if it isn't the complete product. (unless otherwise stated.)
Source of info or it's not true.
Breaking into a car and stealing the radio is still stealing; so is taking part of a game (sound, textures, source code, models, etc).
So basically garrys mod stole from valve.
what.Garry and VALVe made a deal, he gets the source code and VALVe gets 50% profits.
still piracy without the game