Really these operations are so standard, your vet could probably do them in his sleep! They should be fine. There is always a risk both in animals and humans to go under anesthesia, I always pay extra for blood work prior to the operation just to be safe.
After it is over, you need them in separate rooms, in darkness if you can so they can sleep it off. The males recover quickly. You don't want them anywhere that they can jump up on things. Your vet will give you a little sheet of instructions to take home of what to do and what to look for.
Thank you for being a responsible pet owner