on all the character development talk:
I still find the value of characters to be almost nil in this game.
As long as I have 12,000 heavy infantry and 3-5 support cohorts, I am going to kick the butt of a unit with the best general ever who has 5,000 heavy's and 3,000 other.
I am going to get revolts with great governers and loyalty loss from great characters as likely as I am from others.
I am not going to get to the 25th level of Tech, which doesn't even really do much for me, until about 2 years before the end of the game. Not even when you own the whole map. The "technology" tree in this game compared to HOI and CK is not even interesting. There only so many national ideas, and it is easier to get through the game (because of stability loss) without changing them than by upgrading.
The other thing about the technology tree, is that well, everyone gets exactly the same things, no matter where they're from, or how much effort they devote to developing it.
I think if you are going to make the development of technology so abstract just have it pop up at a certain period in history for all players. Sure you still need a council member assigned to it, or maybe you can't build the buildings associated with that field. e.g. if you naval head's skill is +40% it affects the building speed of all ships in an according way. If your military head is +90% it allows you to maybe build faster than the next guy. If your civil guy has a great score buildings go up faster, if your priest has a bad score, good luck getting omens. Just another suggestion.
You get the buildings based on discovery of a tech as well, and again, if you play it well, it doesn't matter in 1 player who much fort/wall you have, you will never give up enough ground to matter. The only real advantage is supplying a massive army. But if you have a decent navy, you only need a few central locations that can support them and move them by ship to where they need to go.