I will say a prayer that his surgery goes well!! My little one has had one true surgery, but has been under anesthesia twice. Once she had to have some skin tags removed from her cheek the side of her head, she was about 1.5 years old. That wasn't too bad, but I was a nervous wreck and had DH there, but had to comfort him(lol)! Second time I did by myself, DH was out of town, and she had to have a piece of sponge removed from her nose. Noone could get it out without putting her under because it had caused an infection and noone could see what I saw. So she was put under and it was removed. Easy recovery, but again...made me nervous to know she was going "under" once again. Good luck and I'm sure that everything will be fine!
My brother had a hydroseal(similar to a hernia) repaired when he was about 2. He's 17 now, but I still remember it. He was swollen and it was hard for him to go pee and actually HIT the toilet because of the swelling. His recovery was pretty easy, though.