As far as skijoring, I would start teach him the mushing commands on walks and in your home. Say the words everytime you move forward at a run, move right, move left. Use treats too

I can get more specific if you need, but you said he already knows some commands, so I assume that you know

Also, get him used to the harness. You'll need to get him an X-back harness (a great site is Alpine Outfitters). I would hook that up to him around the house, just to get him used to it for a little while. When he doesn't mind wearing it, then you can take him out running (on a leash) with you just to get used to running in it and using the commands

That's how I would start!
Neutring a dog does NOT make him lose the desire to run, if my Koda is any indication. I think that perhaps if you were sled dog racing it might have an effect on his speed? But Koda runs and loves to bikejor with me, so I wouldn't say that neutering has an effect.
It depends which CKC he is registered: Continental Kennel Club or Canadian Kennel Club. The Canadian club is reputable, the Continental club is not. Continental is considered by some to be a "puppy mill club" because they don't hold shows and all you need to do is basically send in a picture of your dog and they register it. AKC and Canadian Kennel Club are much more strict and they hold shows.
If you're not an experienced breeder, or if you're not planning to breed as a living/with purpose, my personal opinion is that there is no need to keep an intact dog. Laura Turner created a pretty great list of questions regarding the breeding of dogs... here's a link to her argument:
So You Want to Breed Your Dog?
Lastly, for potty training, check out a sticky I created.
Potty Training We had to retrain Koda when we got him too and the advice I ALWAYS give is "Start over at Step 1 as if he was a puppy." This should help!