Hi,
I'm not a doctor, obviously, but here are my thoughts especially based on my surgical experience and recovery and what my doc told me.
Facial issues are pretty common. I had weird sensations and a few weeks of paralyzation. but it all came back to pretty much normal. My doc gave me steroids to help the facial nerve recover after surgery. because it's nerves not muscles, I don't think there's much we can do to speed up the healing. Just have to let it happen.
regarding the hearing/balance nerve being severed: It seems to me a lot of times patients don't know this (which surprises me) but the two balance nerves are almost ALWAYS REMOVED as part of this surgery. That's where the tumor grows and they remove them so it doesn't come back. Maybe I"m mis informed about this, but I don't think so. If they left a sliver on your facial nerve, then that nerve was not cut, but may have experienced some trauma from the surgery (thus the symptoms you're now having). The hearing nerve was likely not severed, but it is extremely delicate and it doesn't take much disruption for the hearing to disappear.
Right arm: could be because you're on your side and strapped down during the surgery. I had a ton of neck soreness and weird body aches afterward.
those are my thoughts. I wish you good luck in your recovery.