Dude, you could put fluffy stuffed bunnies on ropes behind elephants and they would still rock. A chariot would just be superfluous. Awesome-looking, but superfluous.
I should give drawing that a go 
Wouldn't the penalty for ranged units apply to their melee attack as well? That makes them next to useless in woods altogether, despite some of them actively hunting in woodlands as a living.
Aye, I definitely agree that desert penalties should be much lower. I was thinking up to and inclusive of -4. With perhaps up to +2 for hardcore desert troops. I find there is no point in me ever using desert troops when I'm in the Middle-East because the better stamina doesn't make up for the severe lack of defence they have. Combat bonuses/penalties might give me, and others, pause for thought.
I'll have a play around with these at the weekend when/if I've sorted out a couple of things in the DMB. I'm having trouble with a couple of them at the moment