I agree. This post by Sebastian would be a good start for such things: https://zoteromusings.wordpress.com/2013/10/28/writing-csl-features-and-best-practices/
Yeah, something like this.
Perhaps as an appendix here?
I don’t think it belongs in the spec; does it?
Maybe simply published alongside it?
And yeah, Sebastian’s post is an excellent start.
No, not really in the spec.
Alongside is good. But it should be clear that there are some explicit expectations so that users can rely on these things.
Can include a link to it from the spec?
Yes, would be ok. But where should we have these recommendations.