"1) What are the advantages of getting separate feeds from BATS/EDGEX etc. instead of using the consolidated then? ... But how can you get a competitive advantage if RegNMS forces exchanges to execute you at NBBO anyways."
The low latency guys send ISO orders, which means that they are indicating that they have sent orders to hit any available protected quotes and the exchange can execute the order regardless of its view of the NBBO.
"2) Another question I have is, let's say I send a DMA marketable limit order to BATS specifically to get the liquidity rebate fees and because there's a price improvement for that marketable order; BATS is obligated to re-direct my order to ARCA, do I still get to collect the rebate fee structure from BATS or is that order technically under the fee structure of ARCA."
You're mixing up a lot of terms here. If you send a marketable order (limit or otherwise), you're removing liquidity, which on most exchanges means you'll pay a liquidity removal fee. If you send a non-marketable limit order, you're adding liquidity and at most exchanges you'll collect a rebate if your order fills.
The low latency guys send ISO orders, which means that they are indicating that they have sent orders to hit any available protected quotes and the exchange can execute the order regardless of its view of the NBBO.
"2) Another question I have is, let's say I send a DMA marketable limit order to BATS specifically to get the liquidity rebate fees and because there's a price improvement for that marketable order; BATS is obligated to re-direct my order to ARCA, do I still get to collect the rebate fee structure from BATS or is that order technically under the fee structure of ARCA."
You're mixing up a lot of terms here. If you send a marketable order (limit or otherwise), you're removing liquidity, which on most exchanges means you'll pay a liquidity removal fee. If you send a non-marketable limit order, you're adding liquidity and at most exchanges you'll collect a rebate if your order fills.