"There are no specific conditions against them being randomly generated" is all I needed to know. Let the hunt begin :D
Thanks for all the answers, oddly enough I was editing my post while you were finishing yours, I managed to find and correct the spelling problem for point 4.
You were super useful, I will add those lines to the files at once!
EDIT: Uh, should I add 'trainee' beside 'trainer'?
EDIT2: The Trainer job now works as it should, thanks.
About point 3: what I meant is that if I have a slave do, let's say, entertainment, or hunting, that slave will eventually not only get better at his\her job, but also gain enough normal XP to actually level up. Farm jobs don't really give experience, whereas it would be useful\realistic if I could add strength\agility to farmhands\milkmaids without having to resort to take them out to tag along while I fight bandits.