First of all - there number of unit types is very limited - heavy, light, missile and spearmen, I think, which limits the possibilities a lot.
It does. There are some special types, they are listed in both of the descr_formations, but it's still no enough sometimes.

The other problem is a little bigger - the game says it's NOT compatible with vanilla in multiplayer when I've made these changes!
No, it probably won't be.

And I'm (the one man form mod team) in EB now, so my vanilla mod is currently halted.