Hey, alright so to answer the first question you can play against other players but connections are shady for right now as beta 2 just came out.  The AI is alright so far play is fairly challenging and then have 4 difficulties.  Play right now is only online but you can host games and play vs. only computers.  There are 3 maps, a 3v3, 4v4, and 5v5.  6 available demigods of which 4 are assasins and 2 are generals.  When you are one of the 4 assassins you only play one unit but you have a big skill tree with spells to pick from and items to buy as you level an dmake money.  If you are a general however you play a similar game as the assassins except you can purchase idols that spawn you up to 12 creeps.  On top of these 12 generals have their own special units that spawn under different conditions (% chance when you kill and enemy unit).  Also as far as I know right now the beta is still open meaning that if you bought the game you could play after you downloaded it.  Before you buy it I would suggest that you look throught the forums here for posts about how to get the beta because I know I have seen some about it and make sure you can still get in.  The game is a work in progress right now so it isn't exhilarating yet but as a beta tester you have some input.  Let me know if I missed some part of your question.