What a cutie pie.

I agree, have him neutered! There is no difference between death rates in neutering a puppy or a senior dog --- infact, there has never been a single death or complication from the newer anasthetics. Ask your vet for an inhalent anasthetic. In the long run, your dog will be alot happier and healthier. Right now he is at risk of prostate and testicular cancer. You virtually eliminate those by neutering. He is also probably very sexually frustrated inside. Dogs can be quite vengeful, which could be another reason he is peeing in inappropriate places -- he might be angry because he isn't breeding. He also won't try to "roam" and he will be less aggressive. I'll bet that once you neuter him his marking problem will go away.

Good luck!