Questions about the gameplay of Heroes 6.

In my opinion, it's impossible. You build one, but all the others are useless.

I'm afraid that here, it's just computer cheating at work. And there's nothing you can do about it...

I think the second option is more reliable. You just need to act boldly. First, stomp on Wait to let the liches move, and then attack the tower with all the beasts. Well, of course, this is assuming that no one else is getting in the way.