Oh my gosh...I did not know that your dog was not neutered
Defiantly a HUGE PROBLEM. This will only get worse if he is not neutered. If you do go through with the surgery, please know that it will take a few weeks for his hormones to filter out of his system, so an immediate behavior change can not be expected. I would also purchase D.A.P. comfort zone and reinforce potty training! Intact males will almost always mark in the house. A lot of times this starts later in life after they have matured. Outside things can trigger it as well, like neighbors having a female dog in heat, or other dogs that your dog is smelling that are near his territory. There is no reason to keep your dog intact, and it's not a waste of money, as there are many health benfefits, not to mention a happier and better adjusted pet.
The #1 dog that gets hit by cars is an INTACT male, not to mention accidental breedings that lead to so many euthanized dogs each year. Even if you don't think that either of the above are possible in your situation, be responsible and GET YOUR DOG NEUTERED!!!!