It doesn't need an additonal power cord to connect to it. What you plug into the eSATA will require the power (well... this how my Antec 1200 case is). If you list your actual case, we might be able to confirm this is all that is needed.
You are correct on changing the controller to ACHI, which gives you the hot swap capabilities. Otherwise, you have to plug in the device and restart to get it to connect.