I’m new to Coda, but I’ve learned a few things on MY Coda journey about this! In this post Disable expand row button in the table for user restriction - #4 by Shannon_Bradley I found the solution to the hidden column part.
In this one Disable hover information in Shared Doc - #2 by joost_mineur I learned the not quite intuitive setting for making sync pages properly read only.
Hope this helps!