I created a village today, and it took at least five hours. The houses are larger than an average villager house, so I was wondering if I could put two jobs in each house. For example, a librarian and a weaponsmith in one house. I'm worried that they would keep switching jobs and get mixed up, while other villagers would also change their jobs once they enter the house (due to the blocks inside.) And how come my villagers can't climb up stairs? I have created two houses that have two floors, and they never seem to use it.. Sometimes when I enter one of my houses there's always this one villager who's on the stairs, but just stands still, staring at me. Weird :/
One way to make sure they keep their professions is to trade with a villager once it has the desired profession. Trading will villagers will lock their professions. As far as the multi level homes, if the second floor is more than about 4 blocks above the floor, they might not be able to use it effectively. Villager pathfinding is not very good vertically.