Does this product come with a power cord?

This product is USB powered and comes with a USB cable. No other power cord is needed.

Do I plug in both USB ends to upload data from storage? /

You probably need only plug in the one end that is the shortest distance to the end that plugs into the external enclosure. If your USB socket doesn't put out enough power to operate the drive then you need to plug in the other end into a second socket.