On mercenaries - It would be fun if a "mercenary" company were formed around each nation, using one of their actual randomly appearing heroes as the leader, and a thematically sensible contingent of high end troops from that nation. At game start, each nation IN the game would have their company turned off, all the nations NOT in the game, would exist in that form, as "adventuring warriors from a far off land".
On event cap - Ultimately I think this is the #1 thing that NEEDS to be done. Misf2-3 players consistently state that the idea is to grow so fast anyways, that you meet and exceed that limit as early as possible, thus your relative gains are past the fulcrum of statistical balance for most of the game. I am not so sure about 50 events, but if the cap were even raised to 10 events, it would greatly alter the overall perspective on Luck scale, I'm sure, and find it not only more competitive in larger maps, but more enjoyable to play with.
If it were possible to cap "territory loss" events at the same time, that would be nice though..... Say on a 400 province map, 5 players left in contention with ~80 provinces apiece, someone suddenly gets 10 barbarians deep in his back territory where he hasn't been producing troops - ironically sieging his nearest castles in the area..... Luck needs to be made more relevant, without suddenly having the power to decisively win or lose the game due to 1 turn worth of completely unexpected events (I know, if you have 80 territories, you should be able to afford some PD, but what if you are Nief or a monkey nation? then what!
).
Oh and Xietor, you do know they finally raised the unit cap?
So don't lose hope yet.