I can't answer all of these, but I'll answer what I can.
1.) I know at Epcot there's a pin board in the America pavilion (it's where a cast member sits outside the gift shop where kids can get Duffy and Perry figures on a stick, that they can color in, and there's also one at the main pin trading spot (right behind Spaceship Earth). As for the resorts, the gift shops tend to have them, but when I last stayed at Port Orleans, they also had one where the bicycle rentals are. I'm sure other folks can chime in to inform you of other places.
2.) I can't pinpoint any specific cast members that may or may not have LE's, but I did manage to get a 2004 Annual Passholder Magic Kingdom pin (LE 7000) from a cast member in Epcot last week, where the pin cart is between Canada and the UK. *But*, I saw another guest trade it to the cast member, and I traded her for it before she even got it on her lanyard (it was just a matter of right time/right place, luck of the draw kind of thing.)
3.) I still haven't met Scoop yet, but I've been told he's at MK Sunday through either Tuesday or Wednesday, and from my understanding, he's only there until around 1pm.
4.) Yes, folks still set up at Epcot. I see people at the tables every time I go, though there are only 2 tables now, and sometimes there may only be one person trading. I know one guy that I traded with this past Wednesday afternoon said that he's there every Wednesday. He had some nice LE's as well as more standard fare (hidden mickeys and such). I actually traded him a Mechanical Kingdom Goofy (6 of 6 in the Surprise Release pin set) for a Jack Skellington Poster Pin with easel (2013) still in its box.
5.) Sorry, I literally have no idea who King Pin is (I'm new to pin trading and collecting, having only started back during Star Wars Weekends this year.)
6.) AFAIK, you can trade any pin (with a CM) for any pin on their lanyard, but I haven't collected or traded for any vinylmation pins, so I could be wrong on this.
Hope this info is at least somewhat helpful, and that someone else more knowledgeable can chime in to fill in what I don't know, and to correct me anywhere I may be wrong.
Good luck, have fun, and happy trading!
-George