Multiple bookings question

My wife is a college prof who does a study abroad to Europe for 6 weeks every year. During the trip she has 3 nights in Madrid booking 10 rooms each night on average. Also she does 2 to 4 conferences each year for about 20 nights. Last year she did Puerto Rico for 5 nights and NY at the W for 6. We never looked at doing a rewards program before until listening to Clark Howard. She has complete control over her booking options as she has to prepay for the trips and is then reimbursed 100% plus $78 per day for per diem.

My question is if we were to do the Ambassador would she be able to take advantage of booking all those rooms in her name? and how would that work. Also if we cannot do this on Ambassador would we be better served on another program?

Another ? is we currently use our USAA 2% cash back on all purchases would we be better served getting a specific card geared toward this?

Thanks