So I have Kodi installed on a chromebox, and I can watch everything off my PLEX server on the NAS. If I wanted to add TV I need to first add an IPTV client (which one is most popular?) and then either purchase a subscription from one of the services in the sticky or else find a bunch of m3u's? Plus I will need a guide (EPG) client and service? Is all of this correct?
"I need to first add an IPTV client (which one is most popular?) and then either purchase a subscription from one of the services in the sticky"
Yes correct. The different providers use different IPTV clients on Kodi, I listed some here: http://pwwtech.blogspot.co.uk/2016/02/iptv-providers.html
Out of interest, how is your Chromebox with Kodi on? What make is it?