What restrictions are there for creating new classes (other than being unable to create new Force-using classes)? i.e. is it possible to add Feats that are specifically for original classes to new classes?
  Having not attempted to create new classes myself I can't be of direct help, what I do know is all the force using classes are hard coded and as such modify them cannot be discussed her as to change them violates the EULA... however what I can do is give you some thread links which will help ;) 
 Neutral Prestige Question (
http://www.lucasforums.com/showthread.php?t=165996&highlight=class+restrictions) 
 Darkkender, Stoffe and other veteran modder class discission (click me) (
http://www.lucasforums.com/showthread.php?t=148287&highlight=class+restrictions) 
 Classes and 2DA Editing (
http://www.lucasforums.com/showthread.php?t=122830&highlight=class+restrictions)  
 What restrictions are there to creating new Feats? 
 I often find downloading others mods similar to what I want to do and seeing what they did is helpful... As such you may wish to review the following mod of RedRobs.... 
 RedRob's Species Specific Feats (
http://www.lucasforums.com/showthread.php?t=183411) 
 Is it possible to create new Lightsaber Forms? (They count as Force Powers, right?)
 [/LIST] 
 I had another question and I thought I'd post it here rather than creating a new thread 
 As a moderator, common sense like this can only be applauded :) 
 . Anyway, the question is: 
 Is there a built-in variable or function which determines if there is a weapon in a specific target's off-hand (and which preferably returns a boolean)? 
 Unfortunately not being a scripter I can't help with it :( Welcome to the forums though! :)