What happens behind the scenes in Early Decision (ED)?

Okay, so when a school meets full need and includes say a $2500 work study and a $3500 loan, what is that? Does it mean e.g. working at the School Book store for X hours without pay? Or do you earn a salary that you may or may not choose to put towards tuition?

As for the loans, are we talking 8% interest? 11% interest? 4% interest. Obviously it varies but are they generally a reasonable rate compared to outside student loans? Who is the loan grantor? You’re paying the college back? Or do they hook you up with XYZ bank for it. Are you pre-approved?

Sorry for all of the questions. I just want to have as much understanding as I can before a decision release (Dec 15th) so that we can proceed with an informed decision and not an emotional one. I don’t want to ask the school because I’m trying to fly below the radar until they reach a decision so as not to interfere with that outcome.