Have a look at these threads. They are lengthy and things change throughout, but they will hopefully explain.
http://www.northstandchat.com/showthread.php?330674-Kodi-streams&highlight=kodi
http://www.northstandchat.com/showthread.php?335161-Kodi-tv-guide-find-channels-easily
I have found that NowTv works better using the box plugged into the TV rather than watching on a laptop/PC whatever. Have never had any buffering problems and my broadband is slow (no fibre available)