I just had my bunny neutered a month ago at the same age. My vet did supply some painkillers for the first three days post-op.
Most of my difficulties centered around my bun bouncing back too quickly. He was a little dopey when I brought him home, but by the next day he was trying to bounce around like normal. I was advised to put him in a smaller cage and take away anything he can climb, but then he got bored and ripped his stitches out. And he happened to do it on a Saturday when his vet was away. I had to take him to another vet and pay $145 for them to glue the incision and give me antibiotics to take home (which was more than his neuter cost). The glue didn’t hold, so my regular vet stapled him (no cost because he was neutered there and this was included in their after care). I also put him back in the larger cage and gave him his toys back to distract him. Thankfully that lasted and his incision healed fine. If I were to do it again, I wouldn’t have put him in the smaller cage and taken his toys. Ya, he may have still chewed his stitches, but maybe he wouldn’t have been so persistent if he wasn’t bored.
Now he is one of those rare cuddly bunnies, but with all the handling, traveling to and from the vet (30 minutes each way), checking his incision daily, and medications twice a day, he got really grumpy. I have heard its normal for them to get grumpy due to the hormone changes that happen after surgery, but he was outright mad at me. He growled at me whenever I went near his cage and my husband had to take over his care. But if my husband put him on the couch he would still snuggle up to me; guess I wasn’t a threat there. It has been one month since his surgery and he is completely back to his normal personality now.
As far as your other buns, consensus seems to be to wait one month after his neutering before reintroducing him to his ladies. The four vets we saw and the rescues I was in contact with before getting my second bun said that this is the magic length of time before his hormones settle and he stops producing sperm. It is also highly recommended to spay your female rabbits, it is actually more important than neutering a male. Rabbits have a high risk of uterin and ovarian problems and 80% of unspayed females don’t live past 3 because of it. People neuter male rabbits to stop behavioural issues, but for females there is also important medical reasons. And unfortunately it is dangerous to have any rabbit spayed or neutered because it is surgery. You will probably have to listen to a scary lecture and then sign a waiver when you take your male in; I did. I almost ran back out the door but I had to keep telling myself it is for the best and I needed to trust the research I did before choosing my bunny vet.