I think you have asked every questions that I have absolutely no clue to.
I'm a bit puzzled that the game stated that you could only have one person in that particular career. I've had families with several of them working the same career before and it never gave me notice that I could not do this.
I hope you get the answers you need, I will be checking back on this thread because I'm curious about the answers you get.
He just makes my belly button smilez!