RE: To fix or not to fix
I got my English Setter from an animal rescue. To adopt him you had to fix him soI had no choice. It hasn't hurt him a bit. He hunts as hard as he can and hunts well. Furthermore, he no longer sprays things and he is friendlier for some reason. Don't worry about it. If he is from a shelter, I'm guessing he doesn't have papers(which my dog doesn't) so you can't breed him.
Dogs from shelters can be timid. They need to be loved and socialized very well before you hunt over them. It took me about 1 1/2 years to get my dog ready to hunt. Be careful in his training.