The create noble/clergy button are just for just starting out as a count or minor duke when U have no influence and basically no court.
My strategy is to grow the culture so I keep my retinue down below 30 when I can. Kill off a few old spinsters in the court for the intrigue experience. Train your daughters/female kin in intrigue, and they become perfect accomplices for murder (there, I said it).
Learned this from CK(i); To grow your culture marry debutants in your court to others of your culture only. Generally refuse any offers of marriage outside your culture.
When you character begins to conquer lands he should then have sufficient lowborns or unlanded nobility to fill the posts. Basically, going forward, there'll be enough young blood to be able to pick and choose.
Oh, for council, look beyond culture (but w/i one's religion) for only the best. One can still marry them matiliniarly (sp) to grow one's dynasty--that's not hard.