Hi Jackie, glad to hear from you again.
First take a deep breath & relax... It sounds as if you're running :D Destress yourself :) This is one of those matters that can seem to spin out of control... just think of it like taking baby steps.
Something to keep in mind:
Ok, If you do get him, I would suggest having him neutered as one of the first things you do. An undescended testicle almost is guaranteed to become cancerous. Not sure about a semi-dec. one (ah, the things you don't have to worry about with bitches ;) )
First off:
If the breeder allows you to (I think she would), have her meet with you & your girls on neutral ground, like a nearby park. Just somewhere off her property & without any of the other dogs around. Have your girls come up & just sit (on a picnic blanket) and watch what he does. Is he interested in them? How does he react. If he relaxes into a liedown or wants to play, that's good. See how he reacts if the elder (first) takes him for a walk around the park. Then the younger. Does he like them enough to be gently cuddled (this could take more time). The relationship with you & your girls is more important as a first step than pretty much anything else. If he doesn't like them and has no interest in them, that could be a very telling sign. If he just isn't paying attention to anyone except his breeder, try working him with tidbits & a leash. Running him through a sit - walk exercise. Just take it slow & easy.
Ok, if you decide that he might be the one for you, see about taking him on a trial basis. Since he's coming to a new household, I'd think about crate training him. If he's used to comings, goings, & excitement, having his own little spot where he can't get into any trouble does relax dogs. Make it a positive place. Work up to leaving him 15 minutes.. longer.... (If you have questions about how to do crate training, just ask a bit later-- I won't go into it here). But if he's ok after getting used to being alone & he's getting along with you, then you have your dog. :D
Seriously, it is easier to do this with an adult. If you had a puppy, other factors get involved. It also helps to bond if someone takes him through obediance school. It sounds as if he's basically like a puppy, except he'll have the maturity of an adult to handle a new environment.
I hope this calms & gives you some ideas.
good luck
toodles