How to care for a wounded Rooster??

Our pet rooster was attacked by a dog. There doesn't appear to be any broken bones. He has feathers missing on both sides under the wing area. He must've been flipped onto his back and attacked from that angle. He can walk, but is very sore. My husband brought him in the house and wrapped him in a towel when we discovered he'd been attacked (about an hour after the attack; I heard it not knowing what it was) to keep him warm most of the evening. We tried putting him in the coop but after a short time he was shivering, probably shock, so we brought him back in. He spent the night in our bedroom in a pet carrier. Today he seemed a little better so my husband had taken him out twice and let him in the yard for a little fresh air and sunshine and to walk a little. He isn't eating or drinking much and is still not back to normal obviously. He's back in the carrier and seems to be resting well in our room but we don't know how to get him to eat or drink more. I read online that vegetables are good for their immune system which can be compromised from an attack. He has feathers missing and there was some minor bleeding, but no obvious punctures. My questions are:

1)How do we get him to eat and what does he want to eat?
2) How long should we keep him quiet and resting in the carrier/when is it safe to put him back out in the coupe?
3) What should we watch for so that he doesn't get any infections or get sick?

4)Are there any particular ointments to put on his wounded skin where the feathers are gone?

5) When do we know if he should see a vet?

Any other advice would be helpful. He's a cute little bird, we don't want to lose him
Thank you