1) A. Assuming your son is a qualified undergraduate (first 4 years at accredited school) - Yes, you can claim expenses other than tuition for American Opportunity Credit (AOC). Expenses must be course related, and can include course fees, books, and 'materials', which may include (eg) a required laptop. General expenses, such as student activity fees are normally Not allowed for computing tax benefits.
1) B. To claim education benefits without a 1098-T is legal, but you can expect several months delay for processing. Consider mailing in your return with documentation of attendance and list of expenses.
1) C. For details on education tax benefits, see https://www.irs.gov/publications/p970
2) Yes, Modified AGI is normally higher than unadjusted AGI. MAGI is defined differently for different purposes; can be higher/lower.
