I do own mount & blade (Albeit the more recent "With Fire and Sword") and it is a pretty great engine to work on. I have several years experience with coding games and I understand the M&B coding pretty well too, if a project like M&B: New Horizon's would come out I volunteer to do some coding work. One tip is to use "With Fire and Sword" as that is a further build on upon Warband and it features period accurate muskets, pistols & grenades already.
Suggest you look at the "Hearts of Oak" forum - we are looking to move towards using the Unreal engine
