-You can use hotkeys to attack. Hotkey is written in the skill name in quotes.
-Priests have and ether body skill, that makes them invulnerable to physical damage.
-If wizard will concentrate all the army in one point, he will become defenceless and easy to be killed. And also there is no strong demons in game start. The better one can be only build in future. Without upgrades basic demons are slow, weak, have low damage, and so they are vulnerable to ranged attack. Also, you need to kill a pudge near gates to open them. So wizard can't concentrate all the army.
-About Fog skill: hmm, it's meant that you will cast it when you will be under ether body skill. Also, you can't win this game alone, teamplay is important here.
In 1.1 version I'll make weapon enchaments that will increase mana / hp and later maybe new skills.