Got my bolt extractors in the mail and tried the transmission fluid change again. All the bolt extractor did to my drain plug was turn a rounded off hex bolt into a perfectly round bolt without loosening it a bit. Even my impact wrench couldn't get it off. I was able to get the shift linkage bracket out of the way, though. I really don't want to drop a pan full of fluid, though, so I bought a replacement pan with drain plug and I'll try the whole process a third time when it gets in.
I also fixed my dim interior LED issue following the steps in this thread:
http://www.cadillacforums.com/forum...999/567386-dreaded-dim-led-map-light-fix.html