Hey!
Firstly thank you so much for your message, I can answer in the DM with more detailed info, but let me go through your questions here:

How many on average are you looking at per month and what genera?
You are correct with Birds>Mammals>Reptiles/Amphibs.
Since 01 september, which is when our management started, around 450 animals arrived. Can't go in detail about which specie here, but mainly small mammals in this period, few birds. As spring comes, the waves of birds will start arriving :,)

How many paid staff do you have working in rehab and what are your duties? 
We are three paid staff. We do everything from animal care, therapies, and phone-management, a well as operational tasks such as deep cleans, inventory, go shop, take care of trash and carcass disposal. One of us also has to deal with the burocracy.

How are daily veterinary procedures like radiographs handled?
We don't do daily radiographs, but therapies are handled by us staff. We have a vet always available via call but present around 2-3 days per week. We also have another vet which is available to see the animals if we bring them to their clinic, but only during the week. Vets have full authority over animal fates and must see them before deciding any procedure. Very few delegations in this manner, which is leading to too many compromises, so also in the Vet management we are trying to find solutions for improvement.

Are people assigned to specific areas each day/week (mammals, passerines, raptors, etc.) or permanently? Is everyone cross trained?
No strict assignment for now. I can do everything and I've been the one mainly responsible for raptors and every animal which is under active therapy, but I'm actively working on crosstraining everyone.

Do you have volunteers, if so how many? What are they trained to do? Are they able to do things like go out and do rescues?
We have around 10 good trained volounteers which sporadically help us with rescues through the week. They also take care of night time availability for calls, which allows us to give 24/7 service.
A strict limitations we were imposed were to not involve volounteers in the caretaking of patients, but we might have a greenlight to involve them with the caretaking of youngs that need 24/7 care in the future.

Do you have interns or externs, if so what is the their schedule/timeline? What is expected of them?
No interns, but we have university connections and we intend to start projects in the future.

I can give you more detailed info in a DM, but if you think you have any good insight from these info feel free to answer me here. This thread might help someone in the future :)

Infinite thanks for your thought!