[thesethings]

Threads are not deleted, though they can get hard to find. Definitely save the URL, but don't worry about copy and pasting the contents.

Another great HN tool is http://searchyc.com. You can search submission submission titles, comments, and get feeds for most types of things.

[mtran]

Great. I'm saving all of the links in my Evernote but am wondering if I'll be able to find people in the future through my comments/submissions/threads or if I should save them too! Thanks for your help!

[thesethings]

Yes, you can find people you've interacted with on HN by browsing Threads (top nav) and Next -> Next -> Nexting through your history. Though the URL of each deep page is not permanent, the threads/history do not disappear and you can always browse your history.

URLs of threads/parent/child comments are permanent.

[mtran]

Great info, Thanks a million!