Theres also a rather strict magic limit. Once you get the full game and can get higher level spells and items you will be in love with this game (if your not already).
I can still (not much though) remember the joy i felt when i recieved my copy of dominions 2(which i also stumbled upon by accident) and, later when i discovered this forum my enjoyment increased even more and, as far as i can tell ive played dominions 2 far more than any other game i have (warcraft 3 and a few old n64/gameboy games may come close though)
I think I have the answer to your questions. On your left when looking at a province you see your commanders and thier current orders. By clicking on the order you can give them diffrent orders. Do not confuse this with clicking on the commander icon which just selects the commander. The order is on the lower part on the icon, as default is defend unless you are moving the commander.