You have some choices to make when it comes to using your GI Bill to pay for an education. Because you are eligible for both the older Montgomery GI Bill and the new Post 9/11 GI Bill, you will have the opportunity to choose between the two. If you choose to use the MGIB, you can change to the new bill at any time, but if you change to the new GI Bill, you can’t change back.
Your choice of whether to go with the old or new GI Bill isn’t a simple one. The GI Bill section of the VA web-site has a page to help compare benefits. You will have to look into your expenses, and which bill will provide more benefits for you. Both bills provide 36 months of benefits. However, while the old GI Bill pays a set amount per month, the new GI Bill pays your full tuition, up to a maximum amount. Depending on the school, either one could provide more benefit. You should remember that the new GI Bill also provides up to $1,000 per year for books and supplies, and a monthly housing stipend based on your location (all overseas locations use the same amount).
As far as advanced tuition, I presume you mean advance tuition pay. This is only available if you have applied for benefits, but have not received them due to a delay in processing, and need it to pay for tuition immediately. Up to $3,000 can be advanced to you by the VA in such a circumstance, and you pay for it later.