Q: Berk
A: I myself am not above berking things up ("berk it up" is how we'd often refer to the need to rewrite ordinary text to fill it with cant). But of course the cant comes from old real-world slang, so "berk" is a word that predates Planescape by quite a bit:
http://en.wiktionary.org/wiki/berk
Q: Coliseum Morpheon and Faces of the Tarnished Souk
I know *of* those products (in that I know they exist), but I haven't read them. Of the authors, the only one I know is Clinton Boomer, who can write the hell out of a page. I've only seen bits of RPG work from him, but I love his first novel, The Hole Behind Midnight.
Q: why was planescape set up in a fashion to encourage edition warring? Was it a mistake or oversight or something done for legal reasons?
A: I'm honestly not sure what you mean. Planescape had already been created by the time I joined TSR in 1994 (the boxed set had just come out), so I wasn't part of the mix that made it. If you're referring to the "smarter-than-thou" attitude that other commenters in his thread have mentioned, that was intentional within the setting (showing PCs that the world was much bigger than they thought), but we didn't want *players* to feel like they were being talked down to -- more like they were part of a cool club. Obviously, Planescape was a 2e setting that didn't make the jump to 3e, so no edition warring was intended. Also, the web is full of interviews with Zeb Cook and others about the origins of Planescape. Here's one now:
http://www.theweem.com/2010/09/qa-with-david-zeb-cook-2001/
Q: Why the magic saturation? Was that likewise intentional or did it just happen?
A: We wanted to give the denizens of the planes access to all sorts of crazy stuff to make the game more fun, and likewise PCs often needed more power to hold their own on the planes. Really, we also limited magic in that items could lose their bonuses as they travel away from their home planes, not to mention clerics traveling away from their deities. But I was never a big crunchy rules guy, so I may not be the best person to answer this question.
Q: What are your thoughts on the paizo Era take on planescape back in dungeon magazine?
A: I saw some things here and there, but I didn't pay a lot of attention to the magazines back then. Sorry. I loved that the planes were so wide open that writers could pretty much do whatever they wanted.