For Luna there's her dress which is in the Super S Movie: Link
... then the dress she has in the manga: Link
... and Sailor Luna from the Live Action: Link
As for characters, my bf cosplays Tuxedo Kamen with me, so you can put him down for that.
And as for time, I'm booked solid this year, I really think we should try to do it next year, that will give us more time to find people for the whole cast, and get plans ironed out, and time for costumes to actually get made. Cuz if we're serious about getting a FULL group, we don't want to rush it, and if everyone is making their costumes, then we want them to all look relatively the same, not pulling in random people at the last minute just so we have a full group. But that's just my opinion, lol.