This could really vary depending on what the surgery is and his overall state of health. I had a total colectomy that lasted I think around five or six hours and took a few months to recover completely - my surgeon says I recover exceptionally fast, but I also got an infection which slowed my recovery down a lot.
I've had minor laproscopic surgeries which took about twenty minutes and I felt fine after about forty-eight hours and didn't even need to stay the night in hospital.
If his surgery is being classed as an emergency, that could mean it's more likely to be problematic than if it were routine, though there's really no way to predict.
Make sure they plan which pain killers he'll be given before the surgery and that he has a good supply and repeat prescriptions if necessary when he comes home. You may find he wants medication to help him sleep because pain can really disrupt sleep and I always find anaesthetics give me restless leg syndrome which keeps me up all night too, but which I can get rid of completely with the right sleep meds.
They may give him strict dietary advice to follow - most likely soft food only. It's very common for patients with all sorts of different conditions to be told to have soft food. I'm not sure whether it's the same in all hospitals, but the ones I've been in have an option marked "soft" on all the meal choices for each days menu, and the nurses on the ward gave me lists of what foods to avoid. But it may be he doesn't need to follow a special diet at all.
Recovering from an anaesthetic feels like having the flu. He'll probably want to lie down and not want to eat, that's all normal. He will likely be given instructions for when he can start exercise again, and shouldn't lift anything heavy for a few weeks at least.
If it turns out to be a very major surgery, expect him to be depressed afterwards. For some reason depression often follows major surgeries. Don't blame him if he's very moody or annoyed with you - he likely can't help it - and don't feel you've done anything wrong if he does seem depressed or angry after the surgery. This shouldn't happen with more minor surgeries though.
If you have any more specific questions, just ask. I'm just coming up to my sixth surgery - they're not nice but you get over them and feel better for it.
