This sounds like classic territory marking (especially since he peed ON you). Maybe the ordeal of going to the vet for the neutering stressed him out and he has decided he has to "claim" his home. Whatever the reason, you need to do work to establish yourself as leader and reclaim your house.
Walks are a great way to start, make him walk right next to you or slightly behind you, that helps him know you are the "leader". You walk out the door
first and back into the house
first. When feeding, don't give him the food until he is calmly sitting and waiting (he has to "earn" his food from you).
I'd also work with him a bit as if he was new to your house. Put him on his leash, walk him around your house room to room stopping in every doorway and YOU enter the room first. Make him "sit" before the doorway (especially your bedroom since he's pooping on your bed) and he doesn't enter until you walk in first and "invite" him in. Same thing with the bed, he doesn't go up there unless you invite him to. If you don't want him on your bed at all, take him off every single time he goes up and then stand inbetween him and the bad to "block" him until he walks away, repeat it as many times as you have to until he understands. You have to teach him that these places are YOURS not his.
I'm honestly not sure what correlation his behavior could have with the nuetering, could be a coincidence, could be stress from having to be left at the vet, and idk, but maybe could be a "left over" testosterone thing (it takes a while after nuetering to discepate as far as I know). No matter what though, you need to do some behavior modification with him. I recommend Cesar Millan's books, Amazon has good pricing on them
