Underworld Armor

Hi,

This is my brother's computer, and I guees he has an account here... so anyway. I know there is more to do after you finish all the missions, like the Underworld. I know how to get there, but haven;t decided to go yet. What I want to know is, is it split up like with towns and stuff so I can go to the statue pay 1k and then skip to a certain part or whatever?

I want to know so that if I go to unlock the Armorer, I'll be able to come right back to him and buy a piece or whatever. Thanks.