Yes, you can find the cheat codes on the bottom right corner of the newspapers.
yes you can everything.
yes but it is nowhere near as big as in red dead redemption
you do not level up on single-player free roam on Red Dead Redemption.
I don't think Red Dead Revolver is, but Red Dead Redemption is.
Yes and you get to improve on your profile.
Just go onto multiplayer and join a free roam session.
only if u have XboxLIVE
No you can not
Fight gangs
You find them all around the map
You can hunt, but you can't sell as there are no vendor npcs.
Yes You can but not in single player if you get the Multiplayer Legends And killers you can play as red dead revolver characters online. but not for singleplayer and lairs and cheats and undead nightmare give you zombies and redemption and damnation characters [people from the singleplayer story]