EEE, do you mean Energy-Efficient Ethernet?
Unless you are referring to your device only, EEE is supported in OpenWrt; but:
- it probably won't make your latency go down (there is a slight delay when re-powering the port)
- it has to be supported by the device connected to the port
And pause return...do you mean hardware flow control???
Yea, I doubt many supported devices even had that built in, hardware NAT, yes - pause return, no.