This is more of a Kodi than a NEXTPVR question. When I open TV Guide I'd like it to open up a particular set of channels instead of of 'All Channels'. Is this possible?
That's going to be dependent on the skin you are using. If you're using the default Estuary skin, then I don't think you can. If you're using something else, you might find the support area for that skin and ask there.