I'm trying get my cat to be house cat again. But should I get him spayed or neutered first? I know where take him. But I'm scared he bite the doctor? Should I take him? Cause they are professional so they know what to do with cat that bite if it gets scared. Or Should I wait and train him , so he won't bite? I know getting him neutered now will make less irritating.
Take him to get neutered now! We have several existing questions and answer about spaying and neutering cats, you might want to browse them.
As you note in your question, the vet is a professional who know how to handle your cat. All of your listed training goals will be MUCH easier once he is neutered.