Well, it's obviuos that cavalry can do serious damage.
But I've got some questions about them, I know the bonusses only works if they charged and are only in fight with infantery.
If I charge a infantery model with multiple models and one of my cavalry models is countercharged by another infantery enemy, do I still get the bonus? I don't think so, because it didn't charge the model it's fighting (in my example, that cavalry model has to fight the 'new' enemy, while that model is only in base contact with it).
And what if you charge one model and another model charged you in response, do you get the extra attack but if you win, will only the charged model(s) be knocked prone? So only attempts to wound them are doubled.

Only another cavalry model can deny the charging bonus. If an infantry model charges a cavalry model after he attacked, the rider still gains the extra attack and knock to the ground. So, if the rider wins, he will his dice +1 for the attack twice.

It affects all enemy models in the fight. I beleive it says this in a brief sentance somewhere... Hope this helps.

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By all that you hold dear on this good Earth,
I bid you stand, men of the West!

Yeah the +1 atk and knock down are only negated by cav so
Counter charging with infantry is always a risk, they might also end up in their butts ha