I've been to a number of pin events, including the big one last year, and the one thing I can tell you is that Disney never seems to do things the same way twice, so the most important thing I can tell you is keep your eyes and ears open and be flexible.
I can tell you that last year there were several opportunities to purchase extra pins. One was the grab bag, and everyone got tickets to purchase two grab bags anytime during the breakfast. There was no need to stand in line for that. We just wandered over to the cash registers when the mood hit. When the Logo Store opened there was a big rush to get in and pick up some special pins (Millenium Village CM Dangles). If you missed that stampede you were out of luck because the pins disappeared quickly.
Pin Signing and Auction Preview are things you can do anytime during the morning. They did not have Build-a-Pin last year, but based on the itinerary, you can do that anytime during the 3 days, so I don't think we have to make a point of doing that the first morning. I am guessing Pin Partners is the booths that the DLParis and DL Resort groups set up to show off the pins from those locations. They will also be set up for the whole event.
I think the best change Disney made this year is letting guests register on Thursday so the lines Friday morning should be much smaller. Last year some people didn't even get to eat because they removed the food before everyone had checked in.
So don't worry about not knowing the ropes. Disney makes sure we all get surprised but in the end we all have fun.
