priority by assistents sellection

I have a few questions:

I want the booking system to choose a assistent (back-end) automaticly. But is it possible to give priority to one assistent? So for example the system choose always assistent A first. If already booked the system chooses for assistent B.

And is it possible connect the amount of customers to the availabilty of the assistents?
For example:
Assistent A is available on the opening hours of the salon.
Assistent B is available on thuesday and wendnesday.
So customers per session is 1 except from thuesday and wednesday.

Thanks!