I don’t have an answer for your second question but for your first I do. I would follow what the vet said, but if he gets a little antsy allow more space. Take out anything that could cause damage. I am unsure, but the surgery may keep your pet calm for a few days…

Since he can’t jump to the upper floors of his house, it seems like it would be okay for him to have his regular space on the ground level of his cage.

If the pain reliever is Metacam, that is usually tasty to rabbits, so hopefully he will take it well. You could wrap him in a towel or have someone else hold him while you give him the medicine. Place the syringe into the side of his mouth, not the front. There is a gap between the front and back sets of teeth, so it will be a lot easier to get the syringe in there.

I have never given my rabbits Critical Care after a spay or neuter, because they always ate well afterwards. Some rabbits do go off their feed after surgery, but if he is eating his regular diet, I’m not sure why he would need the Critical Care. That takes longer to syringe in than the pain reliever will, so it could be stressful for him to be held and force fed. I’m not saying to go against your doctor’s orders, but you want to cause your rabbit the least stress possible. You can make up a Critical Care mix and put it in a bowl. Some rabbits will eat it on their own. You can also mix a little baby food into it or mix in some plain canned pumpkin. Or if you think he would lick it off your fingers, you can try it that way. Letting him eat it on his own would surely make him happier than being forced fed.

When my post spay girls come to stay I score a piece of banana or apple and syringe the metacam onto the scored part to soak in then give them the fruit. Never fed them critical care either, they always ate as normal.

I keep them in x pens. I’ve only had one who was a rabble rouser and binkied everywhere when she wasn’t supposed to.

Is it like a tablet? Try and slip it into a banana and see if he will eat it. If you are allowed to crush the tablet, mix it in the applesause. My mom, whos a nurse, has to crush tablets for people who can’t eat so I know its not something new to do it.

How is your boy doing now?

I’m doing critical care right now for my bun, post-GI stasis.
We’ve only fed him one time and it didn’t work too well. The only tips I have that seemed to help were to have him wrapped in a towel to keep him still, support his back and bottom, and try to get the syringe in the corner of his mouth. Point it like you’re putting it in his cheek. I had such trouble finding that spot because he kept moving his head and he’s got so much fur there. Once you get it in their cheek, dispense only a tiny bit at a time and give them a chance to eat it before continuing.
I recommend having a warm damp cloth to wipe off their chin every now and then. Quite a bit drips down and it can be messy!