The MediaWiki software uses a "new reply" button... but I have integrated it with the forums for the discussion pages so you just use the regular forum reply button to discuss the wiki page in question. I guess I need to see if I can change the default text to explain that better.
Yes, anyone can edit the wiki pages. That is the whole point. If you find a new NSX salvage VIN, edit the wiki and add it to the list. You can also upload pictures, screen captures of ads listing it with a salvage title, etc.