I believe the big pins were promotional only. They were designed to be worn on a trade show floor and draw a lot of attention. I was really happy to get to make an official “ask me about” pin for a Monkey Island game.
I always assumed "Skully" was the pirate who's head got knocked off in the beginning cutscene with LeChuck.
You know, the "Aw, how romantic...Ship Ahoy!" guy.
Looking at the full credits though, I find it interesting that he got a name, but Minnie Goodsoup and Charles De Goulash are just "Ghost Bride" and "Ghost Groom".