Like Marecone said.
I think short bios with four lines about leaders performance on war.
I could be a single paragraph, like the ones done by Sunray before the "pre-war bio" idea come up.
You can see them here
http://www.ageod-forum.com/showthread.php?t=3541&page=2
on post number 42
Or it could some short sentences like the "pre-war bios".
I don't think its necessary any photoshop work. Tool-tips would be more than enough, like the one shown on the screeshot.
About LMUBill question
I would want historic war bios.
A lot of player (myself included) don't know nothing about most of the leaders present on game. But they are given to us with capacities and abilities based on his HISTORIC bios, even if in the first turn of the campaign nothing of this have happened "on game".
By knowing some facts about his ACW career i would understand why they are rated as they are rated and apreciate the work AGEod has donde trying to translate this to the game.
Cheers!