1. No idea.
2. Not as far as we've heard. I suspect the devs are too busy finishing up the Incarnate system and other I19 goodies to add stuff for Halloween.
3. It's unlikely. The Magic super booster can give you some nice Haloween-themed costume pieces, but that was released quite a while ago.
4. I don't know about the zone events, but I hope they at least give trick-or-treating to Praetoria. Even if they don't, my Mastermind needs to add to her [Rock] collection 
http://www.fimfiction.net/story/36641/My-Little-Exalt
I would figure there is gonna be ToTing in Praetoria.
Part of why I believe that is there is a contact to turn in salvage to in Praetoria.
Any thing else would be rather wild speculation at this time.
Thank you for the time...
@Travlr (Main) / @Tymers Realm (Test) 
Several discussions usually pop up about halloween but curious onfour questions
1- when does it start?
2 any new content?
3 not going to have to buy a pack are we?
4
usually it is
TOT ( trick a treating)
Raids ( banner,zombies)
night all the time
2 GMS
Will any of these be in praetoria?
as Ood Sigma said....We will sing to you, Doctor. The universe will sing you to your sleep. This song is ending. But the story never ends.