Regarding your original question. You can bank then borrow BUT you cannot borrow the banked points. What you would do is bank this years points and then borrow from next years points. That would leave you a mixture of current and banked points in your next use year.
Regarding your second question, it depends. There is no limit on how many times you borrow, even in consecutive years. However, you cannot borrow two years ahead. I could borrow from 2005 use year into 2004 use year, I could borrow from 2006 use year into 2005 use year. But you cannot borrow from 2006 use year into 2004 use year.
It's a little tricky thinking about it because it's the points applicable when the reservation happens that counts, not WHEN you make it that is the issue.