So ... it's past midnight and I'm just back, so I don't know how coherent I will be, but ... here are my comments:
1 - The wait at Trader Sam's gets longer as it gets later. We had a 35-minute wait at 10:30 on a Saturday night in January, when half of the people staying onsite had to get up at 3am for a marathon. During the week should be a little shorter, but still expect at least a 15-20 minute wait.
2 - Assuming they're still going in then ... do you have any interest in the Star Wars fireworks? We actually really enjoyed them (and we're not Star Wars people). If they are a permanent thing (which I suspect they may be), then you may want a night at DHS to see them.
3 - Orange MB! It's what I got for my most recent trip. And it's perfect for a Halloween trip!
They did for the marathon, so you might be in luck! You just couldn't cover your face, it couldn't drag the ground, and it couldn't be like a big prop type thing (like if you were to dress up as the Death Star and have a big sphere around yourself, that sort of thing they made off-limits).
The difference is ... for runDisney events, you were not allowed to wear your costumes into the park (other than while actually running, of course, and at that point you're wearing a race bib, so people know you're not a real character). For
MNSSHP you can be in the park a few hours before the event, so that won't really fly.
Also ... no toy weapons or capes that go past your waist.
Also ... enforcement at the races was spotty at best. I saw a lot of thing dragging on the ground. Enforcement at the parties may be better because you're going through the regular main entrance.