I think all ideas posted here are valuable and should be implemented. Please make sure to post the design guidelines somewhere prominent.
As for the resource tag, why don't we start with it first and then come up with more attributes as we go along.
To your questions:
- Class prefix: YES. Very useful.
- The resource tag should return HTML fragments.
- Interest yes, time depends :).
APPROVING BOX tag and resource tag with HTML fragments.