MobiPocket ebooks can have either .prc or .mobi as their extension. The MobiPocket format itself has changed over the years and old MOBIs are always in .prc but the newer ones can be .prc or .mobi. The new ones include author and title information that the Kindle will list for you.
However, .prc's from here should all be using the new MOBI format and contain good metadata.
In general, if you open the file using Windows MobiPocket Reader and it does not list author and title, then you might want to add these using mobi2mobi (MobiPerl) or Calibre. With very few exceptions (if any) a DRM free ebook that Windows MobiPocket Reader can read should also work on a Kindle.