You're browsing the GameFAQs Message Boards as a guest. Sign Up for free (or Log In if you already have an account) to be able to post messages, change how messages are displayed, and view media in posts.
No you do not level up offline, Leveling up in multiplayer unlocks weapons, mounts (I.E. - Horses to ride) and different titles you can display above your name. If you want a lot of detailed info on multiplayer including what levels unlock stuff you can go here: http://reddead.wikia.com/wiki/Redemption_Multiplayer