Hi Alexis, and a big forum welcome to you and Robert.
At 2.3 cm, Robert's AN is in the medium category. It is still small enough for radiation treatment, if he is interested in pursuing that. At U. of Michigan, you may get referred to Dr. Telian, who did a presentation at the ANA symposium last August, and is considered to be a very good surgeon.
As far as recovery after surgery, it usually goes something like this. The first 3 days don't count ®. You typically are home by the end of the first week. You need at least a couple of weeks at home, alternating between sleeping and napping, before you can consider facing the world again. For many, going back to work is more likely 4 to 6 weeks later. The first days back at work are tiring, and fatigue comes on easily, so part time at first is often a good idea when possible.
As you can tell from having your next ENT appointment scheduled two weeks out, this is not an emergency situation. Robert has probably had his AN for several years at least. If you can plan a time where sick leave and vacation time can be combined, maybe in the summer, you can manage to handle the down time. Ask neighbors and church members to help out too; many people are more than happy to help, and this is a situation where asking for help is the right thing to do.
The vast majority of medium sized ANs do not cause any of the "horror stories" you may have read about. Robert will get through this fine, like many of the forum members here have done. A year from now it will all be just a pleasant memory.
Take care and let us know how it goes.
Steve