[chevalier teutonic]

Ok I owned the game for some time now but I got some questions. First of: why the hell in the tutorial mission (with the teutonic order and north rus) the arbalesters can't kill a thing but the russian archers kill almost 10 guys a volley?
Second: How come I can't win? I mean, I'm using all the 'normal' tactics: weaken ennemy with archers, attack in front with infantry, attack the flanks with cavalry. Can you explain me why, when I attack a spearmen regiment with another spearmen regiment I can't kill more than 3 of them before my men retreat? Thank you to anyone who is kind enough to answer those questions. Sorry for my english and being a noob.

PS. I won the first English battle because I defended instead of attacking invicible spearmen formations.
PSS. I love the game, I just wish I could understand how it works and then enjoy it fully.