I think time management will be a big part of this game. You wont be able to be good at everything, so players will naturally tend to specialize. They will focus on doing things they enjoy and doing things that are needed in their local community. If you look at the Dev journal on skill progression, you'll see that the Devs intend for only a certain percentage of players to advance to high ranks in any skill over the course of several lifetimes.
For contracts in particular, my understanding is that raising your skill will allow you to write new kinds of contracts, but also allow you to write more complex contracts. So you wouldn't be limited to writing laws to raise your skill. You should have an edge over the competition in most fields.
With regard to OPC's, I believe that they will not be able to increase your skill. They will be somewhat limited in the actions they can perform. With regard to skills, they will be able to practice, or to take actions that the character has mastered, which no longer give EXP but do prevent deterioration of skills.
I really want to hear more about scribing, too. I'd like to open a bookstore, so it's something I am very interested in.