Also, if there are excessive 529 distributions, does the 529 owner or the 529 beneficiary include the excess as income, based on the earnings for that distribution?
It is difficult to give you a complete answer since you do not say if this student is your dependent.
The loans are irrelevant. Only scholarships would affect the 1099-Q and education credits.
If the student is your dependent, you enter the 1098-T from the school and the 1099-Q. TurboTax does the calculation and tells you if there is a credit and/or if there is taxable income. (and who needs to claim what)
If the student is not your dependent, and the 1099-Q is issued to you, you need to touch base with the student so that you both don't use the same education expenses.
If there is tax on a distribution, it is tax paid by the person that is issued the 1099-Q.
It is best (and was designed) for the student to make the distributions or that the funds are transferred directly to the school. That way the 1099-Q and 1098-T will both be issued to the student.