Are you going to keep your withdrawal fees as low as they are today or will they be a bit higher? Btw Shapeshift charges 0.0005 BTC for any operation, which is not that small. I hope your fees will be much less than that.
I really don't any information as nothing has been decided yet. I don't think adding more coins or features will have any effect on withdrawal fees. I imagine the main use of the exchange will be people changing what the get from the faucet and making small deposits from other altcoin faucets so I can't imagine a minimum fee anywhere near that high. I use another gambling site that has many coins and they charge through the spread rather than a fee. I think that would be a good way do it here as well.