You'll probably want the basic tool set released for JO by raven. There are several places you can download it from. Here's a link to the JKFiles download
  http://jediknight.filefront.com/file.info?ID=2888) 
 ModView is a program included with the toolset, you can use it to view models already converted into .glm format, and is very useful for creating new skins for existing models. I have a tutorial on my site that can help those starting out with it. 
 For creating new models you'll probably want to check out a tutorial from one of the more experienced modelers. My personal Favorite is PsykOsith's tutorial.  
http://www3.sympatico.ca/psykopat/) 
 .pk3's are the packed files that the game reads it's data from. They're similar to .zip files and can easily be read and created by winzip.