My boys are soooo more affectionate.....I love the girl aspect....But the boys are great.....They have never marked anything.....

You can get them neutered as early as 4 months and that should settle that issue.....I would just go to the breeders and visit with the pups....If one catches your eye...Then go from there....I am sure she would understand if you don't take one....She hopefully only wants the best for her pups...And if a connection was not made, then better you know now than later...But I think you will really like having a boy....
ALso, with having a 3 yr old already, the pup usually will follow the 3 yr so that will help too in potty training....