To answer your question in your first post: Yes, frequencies associated with trunked systems have to have "On" in the trunked column. (But as you read below, there is more to trunked systems than just frequencies).
From what I can determine, the CSV download you have has all frequencies in Medina county, including conventional and trunked. There appears to be five different trunked systems in Medina.
I really don't know where to begin explaining this, so if I'm rambling and disorganized, I apologize.
Copying and pasting conventional frequencies from a CSV file is a piece of cake. Simply go forth and things will work fine.
It is the exact opposite for a trunked system. All you get are the frequencies, but programming a trunked system requires much more information. You also need to have what type of system it is and the talkgroups for the system. Depending upon what type of system it is, frequencies have to be programmed in a certain order.
Then some of the trunked systems you can receive in Medina have multiple sites. Multiple site trunked systems are dfficult to program in the 796 scanner. Later model scanners (996T and later) do a lot better with multi-site trunked systems.
You would be much better off by discarding that CSV file and using the ARC import feature on your programming software. It will grab the frequencies (in correct order if necessary), the system type and the talkgroup ID numbers. However you can choose only one site because that is all the scanner can deal with effectively.
I also suggest putting each trunked system in its own bank. There is ample "room" in the scanner for doing so.
Please see the attached image: