1) The chat should be added as a sidebar. Opening the chat window blocks the entire map, making it difficult for X amount of teammates to discuss strategy (when strategy is the key component to this game). Why not have the chat option easily available on the side of the game so you don't have to open an annoying chat menu every time you want to say something. Communication is key to winning team games, so why not improve your communication methods.

2) If your teammate becomes an AI, it is a pretty much guarantee loss for your team. The AI is very unpredictable and usually makes erros that are fatal to your strategy. Why not add the option for you to take command of your teammates armies? I'm not saying that you absorb their armies into your color, but you simply have to take two turns. One for you, and one for your partner. This way, you're not royally screwed when your teammate leaves for whatever reason.

3) This is my biggest idea for improved gameplay. I play with two of my friends regularly and we talk on google plus always. We usually win every game (3v3 typically) because we have open communication. And, yes it's fun to win, but after a while I want some better competition. Why not add a clan element to the game? This way, me and my friends can compete against players who play as a team just like us.