I just inherited a Saturn from a friend who got sick of it and I need help on two things:

First, how hard is it to replace the internal battery? They seem to run pretty cheap but I've never opened a console before...

Secondly, and this is probably a dumb question but then I'm new to all this, is there a difference between the separate Panzer Dragoon games and Panzer Dragoon saga? Or is saga just a collection of the earlier games? How much should I expect to pay for Saturn games?

Thanks in advance for the help. I tried doing a search for this stuff but I didn't see either of these topics addressed specifically, so if they were I apologize for missing them.