yes but it is nowhere near as big as in Red Dead Redemption
yes you can everything.
I don't think Red Dead Revolver is, but Red Dead Redemption is.
you do not level up on single-player free roam on Red Dead Redemption.
Yes and you get to improve on your profile.
only if u have XboxLIVE
Just go onto multiplayer and join a free roam session.
You find them all around the map
Fight gangs
No you can not
You can hunt, but you can't sell as there are no vendor npcs.
Yes and you don't need red dead redemption to play
Yes, you can find the cheat codes on the bottom right corner of the newspapers.