Line Infantry, how do you fight with them and why?

[Didz]

I've seen 2-3 times in MTW my chivalric knight Leroy Jenkins themselves into some spears.

In MTW2 units could have the the unit triat 'Impulsive' which meant that they occassionally lose their heads and attack without orders. However, like the 'Fire at will' command, skirmishing and artillery crew behaviour this aspect of the battlefield AI has been screwed up completely in ETW.

Historical reality has little to do with the units or tactics in this game.

Well I think thats the point. And its why ETW is turning into nothing but a pile of rubbish with each successive patch, and why Napoleon Totalwar is probably going to be an equally dissapointing pile of crap.