I went through 20gb or so just from playing the game, I only get 100 a month and this capped my internet, this doesn't sound too great, My internet resets in 3 days but I can't play at the moment. So my question is do the graphics settings contribute to the bandwidth? (I have been running on uber) Secondly a friend said his game was using roughly 300 kB/s is this a normal rate? Does the amount go up and down with the amount of units in the game? And what can I do to minimize the impact on my monthly allowance?
Bandwidth usage will go up and down with the number of units in game. This is basically the only pitfall of a server-client system. Try to play games with fewer people (bots count as people), and fewer planets. To the best of my knowledge, graphics settings shouldn't affect your bandwidth usage in any way.
Like BulletMagnet said, the number of units effects the bandwidth. Currently everything is server side, so there is no offline gameplay. However, when the game is released, there will be offline gameplay. They also have said they will make optimizations so there will be less data transfer.