It depends entirely on how you negotiate the contract If you can find someone to count all of it that’s great for you but typically you would agree on a rate and then go by the amortization schedule. Some people use a flat amount like $100-$150.

Basically like I said it is all in how good you negotiate don't let anyone tell you it is suppose to be this way or that make them tell you that they will not do the way you request.

In my opinion I would ask for 6.5-7% rate and let the amount of principle reduction be based off of an amortization schedule that’s uniform and no questions or disputes later

That will depend solely on the contract you sign. Always have it reviewed by a Real Estate Attorney so he/she can tell you about the clauses. If you want to get easy access to attorneys for reviews, sign up for a pre-paid legal plan that allows reviews. These are generally month to month plans and that could save you hundreds of dollars.