As I understand, when the fed increases a bank's lending window, it is not actually giving more money to the bank. It is akin to increasing the credit limit of the bank. If the bank actually does borrow up to the increased limit, it pays interest on that loan.
That jives with what I've read as well. Also a number is incremented in the database, no currency is actually printed. So when it's returned no currency has to be taken out of supply.
For whatever reason, overnight loans are standard which grossly inflates totals over a period of time (I think it's just conspiracy theorists that use totals like that as they count on people not knowing it's an overnight loan that has been returned). A billion dollars a night for a year is $365B. It doesn't take long at all with a handful of large accounts before you hit $9T.
