No built in wireless in the UT50. Has an Ethernet port your you can by the wireless dongle.
So you'll need the wifi dongle, or to run an ethernet cable from the router to the back of the TV. Then run an optical cable from the optical out to the receiver if you want the sound from the streaming apps to come through your surround system rather than the TV speakers. You only get 2.0 sound that way though, no way to get 5.1 from the TV apps.
So IMO they're pretty useless. Much easier to just use Apps on a Bluray player or game console or Roku/other brand set top box that you can just hook up to the receiver via HDMI and get surround and the video to the TV through receiver etc.