If I understood it correctly, futures won't have any actual transferring of bitcoins so it doesn't matter really.
They're trading futures not bitcoins directly.
This doesn't matter. The HFT arbitrage guys (if they haven't already) will move in to bring the other components of the fragmented market inline. This is just a natural progression with markets becoming more efficient.
All settled in dollars AFAIK.
Yes - you will be able to trade much faster than if bitcoins actually changed hands.
One thing this allows is shorting - unclear what it means wrt current price.