I am a little confused with the hdhomerun setup. their website says that one needs to purchase a $60 annual sub for the DVR and EPG to work. So my question is does that interfere with the TV Guide and recording that I can get with a TVHeadend?
Are you planning on adding it as an IP tuner input? If so, it shouldn't make any difference, in my limited knowledge.
You don't need to pay sd for epg if you are using tvheadend
That $60 fee is for their own DVR software. Currently there is no real integration with that software into Kodi. Tvheadend is cometely separate, and requires no additional payment to SD. If you are using SD's DVR you can use their HDHomeRun View addon, but that does not integrate with Kodi's PVR subsystem.