I have never been but we are going Sept. 29th. This is what I know so far, we have to buy a hard ticket about $38 per adult, children under 3 are free. We can go into the park around 4 pm, but if we are already in the park, then get a wristband. They are doing an anouncement to have regular guests leave if they don't have a wristband.
We can go in costume and then are given a bag to trick or treat at shops and with characters. There is a special parade, special fireworks and decorations. I think the haunted mansion is decorated different also. Again, I have never been.
The rides are open and it sounds fun. See you there.
There is a website link on the disneyworld for special things going on.