2. Full time aid...
If you go full time, you will receive a certain amount of money per month. 12 credits per semester counts as full time. If you take 6 credits per semester, you would receive half of that amount. It won't be the same amount as the cost. the active duty version of the GI bill gives you over $1000 a month for full time status. I dont know the exact amount with the new GI Bill. The reserve version would be considerably less.
4. You can use it either way. That's up to you.
For your other questions, I really don't have an answer just yet.
PO1 Kevin Couture