lucy24 - 9:36 pm on Apr 3, 2013 (gmt 0)
I want to know if I would need to change file extensions
You never need to change extensions. (This is a generic answer, not specific to joomla.) At worst, you'll have to add a line in htaccess that rewrites --not redirects-- from your old extension to the form the CMS uses.
If your old filenaming system is icky, you might take this opportunity to change it. But that's a whole nother question.