About your editors...I really suggest you look into setting up custom user roles if you have something like that going. Something like the "Members" plugin, for instance.
However, since you asked, what you want to do is possible, you'll have to create a custom plugin template for the list so it will display the "private link" (like you can see in the admin list) and the the records can be edited. You'll want to control access to this capability, of course. You'r editors will have to be logged in probably--and that takes us back to the user role plugin.
Repost Writing? Not sure I know what you mean, but it's easy enough to create a custom template for a single record that lays out the data any way you want. Another trick is to use print stylesheets to create a printable version of the single record.
Mail merging is probably best done by exporting the list as a CSV into a spreadsheet program where you can perform the sorting and filtering you will need to set it up for running a mail application.