Borders are very highly strung, and the more "purebred", the tighter the string. Especially if this one came from a real working line, potty training may prove to be the least of your problems. Working dogs need real work to do, and if they don't have it can develop antisocial habits as an outlet.
Hubby's former dog being a Border Collie mix can't have prepared you for the real thing. My Sister and her husband acquired one for exactly the same reason and despite the fact that they had raised/trained other difficult types, they could NOT break their purebred, papered Border of one of his innate compulsions: herding. In his case, the only thing around to "herd" was people- often children. And as is well known, Borders herd by nipping at heels.
They eventually had to put the poor dog down, since people-heel-nipping is considered- quite rightly- BITING.
I tell you this in in the sincere hope that if necessary (and while this one is still young) you reevaluate, perhaps even reconsider whether he's a good match for your situation.
