2. The "more liquidity than MtGox" claim is beyond ridiculous in this case.
if your add BFX orderbook and mtgox orderbook you get exactly that, more orders that on mtgox How are you accomplishing margin trading? IE: do you have a reserve of BTC you are extending credit against?
the BFX exchange and exchange accounts (or money deposited on exchange wallets) are the used like any other exchange, they dont use leverage, you buy with your funds and sell your funds. That is called a "cash account", margin involves a brokerage house extending you credit and allowing you to put a "margin" of that amount up to "maintain" a position that they charge "interest" for the loan.
If your position goes too quickly against you, they do a "margin call", shut down your position and you would lose that deposit you placed to create that leveraged position.
In the Bitcoin world, being that Bitcoin is a fixed asset without the ability to create artificial credit, the only way I can see an actual margin account would be having a reserve you are allowing people to get credit extended to them from.
Any other way would just be calling it "margin" but not really giving them this margin, ie: not everyone could close their margin positions and take their profits at one time.
Please advise,
Dalkore