1. If the old "raw" threads can be locked, with a link saying "stuff went to such and such URL so click here" that would be cool. That way they can be read or re-found if someone traced them, but new stuff won't get added in that ought to go to the new, improved thread.
2. When you combine multiple threads without ordering things in chrono order-- how about putting a pink note at the top alerting people to that fact, and then making each pasted batch a different color?