The monitors may come with VGA or DVI cables but the HDMI is the standard connection for most office dual monitor setups.

Do you need two power cords for two monitors?

Video cables cant transport power, both monitors need to be powered independently. Both monitors need to be connected to the video output of the computer, you cant daisy-chain monitors. Also, your computer must have 2 video outputs, as one output can only be connected to one monitor.