Well you can obviously teach them or have your children tutored for specific skills. I also assume you can use your kids once they come of age for labor on your farm or in your shore front.

You won't be able to manipulate their personalities but you can influence how they grow up. I don't think you'll need to make contracts with your kids for them to do stuff for you, hopefully you can should tell them to do something and they will.

Hopefully NPC kids arent all just carbon copies of each other, I'd like to be able to say "I like bill, bill does the chores while tim is always adventuring all day"

From my understanding each NPC, regardless of where they are a child or adult, will have their own personalities and goals and dreams. So I like your choice of words 'influence.' Where you can lead a horse to water you can't make them drink. So you can't 'force' the children to do what you wish unfortunately. If you are nice and friendly and compliment them often then probably they wouldn't mind helping out with the family business. But if you are mean, short tempered and forceful, perhaps they can't wait to leave home and start their own life where no one belittles them. So I feel you can 'influence' up to a point however if there mind is set against it, well there is not much we can do.

I wonder if you can somehow sign a contract on the childs behalf. Otherwise it will be difficult to send the child to a school owned by another player.

that's the question you raise 4 kids

If child 1 says I want to be a blacksmith, Can they be trained at the best school,,,at what cost ? to bring there generation up to your status level or as close to it. And can this be done at before release or at main release