The minimum account size is $10k at E*Trade. Other brokers may set it higher or lower. The less you have in your account, the harder it will be to avoid blowing out. The minimum margin requirement, set by the exchange, is currently $3938 for the ES, but your broker can set it higher. If you open an account for $10k, you can lose more than that. In that case, you have to find the money somewhere.
Margin requirement (actually, it's a performance bond) is a fixed amount per contract. You could buy 2 contracts with a $10k account. The exchange bases the margin requirement on the value of the underlying instrument and price volatility. The margin requirement changes occasionally. The maintenance margin is the amount required before your broker has to dump your position.
Is there any way to trade the current dow instead of the future dow? And how the hell do I do it from E*Trade, or am I better off with another brokerage?