When we had Keoki neutered in November, we didn't even get a collar {we could have, but chose not to}. We didn't get one when Jazz was spayed last year either.
It was not a problem. Aside from a little licking, he left the wound alone almost completely. The surgeries now are so different than they used to be. Ask your vet if you can skip the collar, leaving the option open to come back and get one if your boy bothers the wound too much.
The vet will probably advise you to keep your boy calm for about ten days….good luck with that, LOL.
I'd stick with short walks just to go potty for the first few days, then maybe begin longer walks -- let your dog guide you on when he's ready for that.
I'd avoid the dog park until he is completely healed.