1. In my 1.01i games, the Austrian AI tends to withdraw his armies to off-map Hungary, never to leave the area again. That off course kills any challenge a game with Prussia might pose as you can simply wipe out some small detachments and occupy Wien.
2. Prisoners of war: now they're little more but a number in the ledger. Why not make it so that you can press them into service (some conscripts in exchange for money and warsupplies (muskets, uniforms))? It was a common practice at the time.
3. It's a matter of taste off course, but some of the leader stats seem a bit off. Like de Soubise's 4-1-1, which is quite high since he 'commanded' the French Army at Rossbach. Hildburghausen on the other hand has a 2-0-0.
Anyway, great job!
Soderini