Discussion threads: Probably yes. My initial thought was to just preserve the -devel mailing list (development topics), but a -users mailing list (end user questions and support) might just be as important, and serve as a fallback to look for answers where the real end user documentation (user manual, etc..) doesn't provide a good answer.
Bug tracker entries: Definitely. Imagine a source code comment line that says "We need to reevaluate the query here because of bug 4711." - people studying the source code will have an easier time understanding decisions and motivations if they can read the history of a bug report (and maybe alternative tries at solving the problem and why the alternative solutions weren't chosen).
Ideally all URLs referenced in source code comments should also be mirrored (wayback machine style). Imagine a tricky algorithm that is based on some scientific paper or article somewhere on the web (with link in the source code) - getting access to that paper/article might be very helpful (or even essential) for understanding the algorithm's inner workings.
2013-05-17 09:46