Regarding arbs vs lbows, I still use archers and lbows much of the time because they can fire over the heads of my foot soldiers, and I like the rapid rate of fire sometimes - especially when I'm on the attack. But I have felt that on the defense it's fantastic to have a couple of arbs. They outrange most everything, especially if you can get a little elevation. I don't know the stats, but they seem to do a better job per-volley at taking out armored targets than longbows, and they don't get the rain penatlies that the other bows do.