MMO-Champion has confirmed that both the Creepy Crate and Feline Familiar will be available this Hallow's End! YAY!
The Creepy Crate quest chain can be started by speaking with an innkeeper in Stormwind or Orgrimmar. After completing the low level and short storyline, players will be prompted with a choice on how to end the chain. Regardless of which choice is made, you will still receive the crate pet. :D
And thankfully, the WoW armory was accurate and the Feline Familiar will cost 150 Tricky Treats. The Hallow's End vendors will be selling the witch-hat kitties. You can gather the treats through dailies, baggies (Headless Horseman holiday loot bag), and other various in-game Halloween events.
I'm not sure what the Feline Familiar animation is, but a cat in a witch hat riding on a mini-broom was datamined along with the Feline Familiar a while back. Could this indicate that this companion will be the first flying feline?! We'll have to wait and see. :)
The Creepy Crate... well there are reports of this pet having quite a hunger for other critters. Apparently it will "walk" over to a critter, and in a haze the critter will be promptly gobbled up. The only trace left behind is your box licking its lips and looking smugly satisfied.
There are still 5.5 (agonizing) hours left until my server starts celebrating Hallow's End, but I'm extremely excited. Midnight couldn't come any sooner!