I would think you would be able to train the dog to be around cats if it was raised as a puppy. You may be able to find one in a rescue that has been raised around cats too.

Potty training difficulty varies with the dog. Just be very consistant. My sister had a westie pup that was awful to potty train. He was from a pet store though which I think that was most of the problem. He was used to going potty in his cage as that's where pet store puppies are kept all the time. I could have him outside for hours and he would not go, bring him inside and the second he was in his kennel he'd go. But I'm sure other westies are not like that, just my personal experience with a westie pup (sure was a cutie...fiesty though!).