Ok.You can increase the chance for a ruler/heir to die to make him a general and send him in combat.
About taking north Africa land. I would only take a few province (central of trade province/rich one) since their land has +50% coring cost. Early game it will cost an arm and a leg to core those province, resulting in lagging behind in admin tech.
I already am behind in Admin tech. I had priority on for military and didn't even realise it was an option. Got frustrated wondering why Admin was going to where and stumbled upon priority button. I must of accidentally clicked it at the beginning of the game.