I can't answer the first question, but the second...like the others have said, it kind of depends on what you want to do. If you're looking to trade for Hidden Mickeys off cast members, then definitely be aware that that is where those purchased scrapper lots end up (sorry if I'm going over territory you already know, btw). Families, newbies, and sharks dump those fakes from eBay right onto the cast lanyards. So getting real Hidden Mickeys is tough (best bet is those packs you can buy, followed by early morning lanyards, or being around when a cast members loads up a fresh lanyard).
If you still want to go ahead with a large lot, hopefully someone else can provide a name (I don't really buy them myself, so no clue).
If you're looking to trade for LE pins or you're starting to get serious about trading for HTF pins and such, then I would take the advice above, and ignore large lots all together. Your best bet is browsing for decent deals on Disneyshopping.com pins or Disney Auctions pins (both on eBay and forums/FB). Pick some popular characters (like Stitch) and try and find deals. Sometimes, you can buy a ds.com or DA lot of about 10-15 pins...those are a safer bet than large lots (harder to fake, especially with backing cards).
It's a fine balance, knowing when you should just buy the pin you want, or try to trade for it. My rule of thumb is, when you can get it for retail or less (whether it's for your collection, or as a trader), and you think it's a decent pin (good character, nice design, seems popular), then grab it! If it seems high, then wait or ignore it. There are some exceptions to that when it comes to Grail-level buying, but for the bulk of pins out there, that works fine.
EDIT: I should mention that be wary of deals that are TOO good on ds.com or DA pins. There have been some counterfeits made of some of them, and some of the sellers get creative and find backing cards to put them on. Of particular note, a lot of the "Jessica as..." and "Tinker Bell as..." pins have been faked.
I know, all these fakes are a huge pain in the butt. Eventually, you'll start to get a feel for when something is a good deal, and when something is a suspicious deal. Pin friends can help with those conversations.