Speaking of siege battles,
How effective will ranged siege engines (catapults and such) be at destroying stronghold walls and other such static defenses? I'm asking because in my experience there is a very thin line between useless/ineffective and overpowered siege engines. For example in BfME1, Gondor were often able to nullify the enemy army's siege capacity by using their wall mounted trebuchets while in games like Age of Empires 2 or some of the Total War games a couple of trebuchets practically take away any point in having a fortified position.
Another problem is that weapons like that tend to make all other, more close up, siege weapons (ladders, battering rams, siege towers) obsolete/needless. I once played a match of AoE2 where my friend and I agreed not to use trebuchets, only catapults (arrows can reach them) and rams, it was a very different game, believe me.
One way, imo, to "solve" this is to make the range of "shooting" siege weapons such that they can be reached by the castle defenses but to also make them "not-so-easy-to-destroy" (make 'em resistant to arrows for example) so that they are able to do good damage while not leaving the defenders helpless against it.
Another way would be to impose special pop caps on siege weapons. For example, a player can have 10 ladders, 5 siege towers and 3 catapults. This will "entice" (read, 'leave him without any choice') the player to use all the siege weapons in his arsenal and not just the "easy" ranged ones.
I was speaking in general terms of course, I do realize that not all races will have access to the same siege weapons/wall defenses.