How much exp do you get for killing another player's hero, if any?
where dö i train heroes.. .
that depends on the hero experience: When a hero dies in battle, the opposing side gets 1XP per Level of the hero (If there are multiple defenders, the XP gets split among the defenders of course, just as with regular units). So for the purpose of gaining fighting experience, killing a unit that eats a lot is the same as killing a super skilled veteran hero.
@Henka#NO you start with your hero trained and alive by default. If he/she dies you can revive him/her by clicking on the skeleton image then the 'Revive hero' button or using a bucket from your inventory