I think that if you train and remember to be constant even if just five minutes a day, socialize well and continually, temperament issues should not be a
pr oblem. Most large dogs do not mark in house. Your female is fixed so that is not an issue.
Teach a solid come and a stop command. And start now.
I peeked at the genetic diseases for labs and they had a few eye conditions listed. Also ED seems more prevalent than HD.