Do you have to do the 36 months of post 911 gi bill consecutively?

I have 2 questions. I will be doing full time spring and fall semesters and taking summer off. Will my post 911 bill just be put on hold and not charge any of the 36 months or will it continue to charge some of the 36 months throughout my summer? Im trying to see if its enough for me to get my bachelors and do you have to show the lease or anything to get the bah?