a)The extent of their accuracy goes as far as saying "Eventually there will be an update" or some other equally vague thing and everyone interpreting it as a prediction. They never really predicted anything.
b)I noticed a lot of people talking about this on the playthegame.com board. "So-and-so-important-guy acted weird when I brought this up..." I'm pretty sure they were all just sick of hearing about it and wondered how anyone could still believe it.
c) The story was completely convoluted and no one really completely understands it. It wasn't well written. More likely it was thought of as they went along.
d)I'd like to point out that they based their hoax off of a viral Treyarch made, and this was only involving for a few people (~30). That's a failure as far as marketing goes.
e)No. They haven't revealed anything about the game. Anyone could have made those.
f)The gknova0 youtube channel is weird. Whenever people dispute anything in the comments of one of their videos, the comment is deleted. If it was real, why would Treyarch care? Also, the video that was copy write claimed was actually claimed by Ben Slack, not Activision.
Creativity wise I thought it was really meh. I don't know, nothing really jumped out at me as being particularly unique or new.