I did wireless connection at first but streaming seemed to get interupted, so I used a ethernet cable to my modem, roku walks you through it all, try wireless first if you want and if it is not fast enough you can always connect switch it to ethernet.
roku works with a wireless home network, very few models actually have an ethernet jack in them, the set up is quite easy, plug the roku into and outlet, plug your roku into your tv via HDMI or A/V cables, the device will automatically look for the strongest wireless signal, from there you can login to your home network and all your wireless services (Netflix) will show up.
Yup (plus power to a wall outlet). Wireless ethernet will work too, but a wired cable is best if practical. Roku is the best way to watch Netflix on a TV, as it has the most practical browsing interface for Netflix.