x) Traders. They do not operate in India. They directly work with MtGox, Bitstamp and X, Y, Z. But normally does not worrk with C in above. Why ? Well the % cut of c in India is a bit ted high for them and they can not justify it. They do a good volume, more than 50 BTC for sure. If you want to open exchange try to eye them. It will be very hard for you to get them in as they are used to work with liquidity which will be chicken egg problem for you.
I trade on MtGox. There is 0 chance I will trade on an exchange that charges 3% each way. Just to enter and exit a trade, it's already a 6% hit.
I used to be a market maker on Bitfloor when it was around. Bitfloor actually paid liquidity providers for each transaction, rather than charging. That's the way to add liquidity to your exchange, especially when you're just starting.