No you can't. You have to work to unlock them. There is one cheat found in the bottom right corner of the newspapers which gives you a suit which allows you to cheat in Poker games.
Yes it is possible by leaving the area and then returning.
No, you can only find it once I'm afraid
yes you can
If you mean in online mode, this is not possible, you start back at level once and you have to work your way back up to get all the weapons and steeds etc.
maximum of five times. once you have done the fifth you unlock john marston :)
they have double exp roughly once ever month, they usually say a week before when it will happen
once downloaded, you should just be able to play it in the co-op menu
You get them to send an invite and once the invite has been received, accept it and you will join that person.
Look at the challenged for it on your outfits section of the menu. Once you have completed all of the challenges, buy the outfit from theives landing
You unlock it once you reach a certain level in multiplayer or you can buy it in the Armadillo gun shop in singleplayer mode.
Usually they will have Double XP once a month. Follow Rockstar on Twitter to see when a Double or Triple XP is coming up
You must complete the set weapon challenges and once you have completed all challenges for that gun, you get a golden version to use