1. Yes. In Load Program guide, add an OTA mode, and select it to be run along with your other EPG method.
2. That can be changed in the future. Yes, it currently scans for all channels.
3. As long as you use the option "In Over-the-air EPG scan (atsc), save programs for channels with empty XMLTV IDs Only...", the OTA EPG data is used only for channels that do not have an xmltv ID.
4. True. See 2. Currently your way of selecting which channel to use OTA data and which channel to use online data is "XMLTV ID".
5. Maybe.