Changing Active Character slots?(FF6Adv)

So I'm going to admit, I'm new to hacking FF6Adv and have very little idea what Im doing.

That said, I'm trying to get Gogo in my party early on, which worked fine for the Magitek armor bit....buut as soon as the 3 party Moogle fight at the beginning starts, Cosmog takes over Gogo's character slot. I heard hex editing can solve this, but I have abolsultely no idea what I'm doing on that front. I've been able to find Gogo's hit points, but not sure what to do from there.

So I guess my questions are...
1. What's a good program I should be using for this?
2. How do I use the program to boot Cosmog and swap him for Gogo?