I think that for many things, just go w/ a standard: "Changes/adjustments/updates to existing policies can and will be made as needed & on a case by case basis" kind of thing (...just so you don't get locked-into something that you may want to adjust at a later date.
Also, as basic as it sounds, I think most sites have definitions, tolerances, and zero-tolerance stuff all easily visible/easy to find for newcomers.
I really doubt that this site will be the 1st site that anyone ever comes to on the Internet...but...it's not impossible that this may be the 1st *forum/Discussion* part of a site that someone may be interested in.
So, again, as basic as it sounds, I'd suggest clearly stating definitions & policies for trolls/trolling, flaming, spamming, bashing, etc.
Once upon a time we all had to find out what these words meant & what the related policies of the site in question are.
Also a good explanation of what's "mod-worthy" and the consequences (if any) for 1, 2, 3, 10, 50, etc "breaking-of-the-rule(s)", etc.