There are characters at breakfast, lunch and dinner. There used to be no walkaround princesses at dinner - that's what changed, they've now added them. It is possible that some persons who would not have otherwise booked dinner are now doing so because there are now princesses there.
Returning to the issue of capacity closure - that is a very real concern on the 4th of July in MK. The parks close in stages for capacity, and if it has closed for you, you will not be allowed in even if you have a reservation - including a prepaid reservation at CRT. So it's a wise suggestion to go as early as possible and stay in the park until after the meal, because if you leave and the park closes while you're gone, you won't get back in.
Stage 1 closing - Parking lots closed, only guests using Disney transportation may access the park. (If you are staying offsite get there early)
Stage 2 - Ticket windows and electronic ticket kiosks closed. Only guests who have previously purchased tickets may enter.
Stage 3 - Only annual passholders and Disney resort guests are admitted.
Stage 4 - No one is admitted.