Looking for the answer to this too to see if its worth getting a FP+ for. The accounts I've read from this weekend I think said that they let the FP+ people in first. No reserved section.
Saw it this morning for the first show. FP has separate entrance and was let in 10 minutes before standby. I got in stand by line 30 minutes before show and was on the 4th row.
Guests with FastPass+ reservations are let into the theatre first and have first choice of seating. Standby guests are then let into the theatre until capacity is reached.