Yes you can, the only things which are blocked are trophies/achievements and autosave
You can do missions for Bonnie MacFarlane in Red Dead Redemption, that is all.
Absolutely not.
yes
do your missions
Do your missions.
No, in undead nightmare you basically kill zombies and do zombie missions
You can do cheats for guns.
you have to do missions
on the storyline there is 51 missions and 18 side missions
i have both and i believe red dead redemption is a lot better as on mafia a lot of the missions are very similar whereas there is a lot more variety in red dead redemption. also red dead redemption has a much better and interactive environment
cheat codes are all around the internet for every game, including red dead redemption. However, if you use the cheats you will be unable to save the game or unlock any achievments. The cheats are easy and fun to remember.
i think no