Im running a tourney which has seom of the elements you have mentioned and I think keeping the rules simple is the best advice I can give.
Mysterious victory conditions, and the like sound like a good idea but many players in mine complained that the huge maps and large amounts of points were too much for them to handle and have fun so starting small and building up to the big battles might be a better way.
And while I dont want to imply that many of the players in my tourney are simpletons (because they are not) any rules you do have should be carefully explained with examples if possible, in fact i found that running several test battles to get things right helps to see if the rules are viable (sometimes they are not even if they look good in theory).
I run a team scoring and player scoring tourney so to encourage cooperation but allow for individual competitiveness, players seem to like seeing how other players are doing.
I have a plethora of various rules which can be dropped on players as fate intends and its adds a bit of spice to the battles as having something which can allow for a certain amount of luck can add to the battle as long as it isnt overpowering.
The battle damages idea is interesting but given the caliber of some of our players that might be consigning a battle damaged player to certain doom, trying to find a system which has some ongoing penalties for bad performance is something which I am working on also but its a delicate balance of handicapping
Finaly think about maps and map dynamics, certain terrain and features can slow battles down or allow certain types of force to get ahead, be aware of what you put on your maps and think about how the battle will likely move (again test battles) as an Urban battle will usually come out much different from a desert one or a map full of choke points.
Anyway good luck with your ideas, its fun to make them come to life and rewarding but can be hard work.
Bis peccare in bello no licet - One cannot blunder twice in war.