This is an excelent mod!
As a 13th c reenactor with some milage, I love the visual style and detail. As a player, I also like the map and the many factions.
The only thing I would like to see (that would not require major reworking of the game itself) is an integration of the Diplomacy mod, and the improved battle/formation AI, which would place this way up there with Brytenwalda as my favorite mod. As far as I know the Diplomancy mod is readily available for integration.
Great job!
*golf clap*
PS: On the issue of leavies, one could have the opportunity of raising a leavy by persuading the leader of a settlement. The leavy will then appear as a separate party, and follow you around untill dismissed or time expires. Your relationship with the settlement and the persuation skill determines the size of the leavy, as well as their morale. If you are that settlements lord or king, you can compell them to muster, but they will not like it at all.
Once their morale drops below a certian point, they will start to go home. They will also avoid more powerfull enemies, like other parties.
In this case you might also have the option of herding them in front of you, like cattle. Of course at the risk of them rebelling if your retinue is to weak, they dislike your, and morale is low.
Quite correctly, this means that you can raise leavies from villages and towns you do not rigthfully own, if you have good enough relations with them. Thus, you could build popular support and start a rebellion with a peasant army, or even convince the villagers of the enemy to join you instead of their lord. (Villages would need to get negative relations with characters they are at war with, of course)
In countries with a relatively weak elite and few strong fortresses, such as (my native) Norway, the power of raised leavies caused attack to be more powerfull than defence, and the warring factions ended up chasing each other around from region to region.
Mass leavies could be very large, but a pain to raise and controll. The feudal system was partly a way to avoid this problem by leaving professional nobles rather than unpredictable peasants, and creating strongpoints that could endure attack.
If, and what kind of, leavies to call could be a choice left to you as a lord. For instance, the french would not like their peasantry armed at all. The Norwegians wanted shield and spear infantry. The English leavied their lowest tiers as archers, where their lack of armour and resovle would not be so disasterous. And so on.
But as a nobleman, your retinue is still your main asset.