The Babadook - a horror gem from Australia

Life is not a bowl of cherries for Amelia (Essie Davis from "The Slap" and "Miss Fisher's Murder Mysteries").
Apart from the fact she is living in Adelaide, she pines for her dead husband, lives in a dilapidated house (that looks like it was decorated by Morticia Addams), has a disturbed six year old, has to contend with a snobby sister, and by day she works in a dementia care facility.
She lives in a dreamlike state, obsessed with her late partner, her weird child and her quest for sleep. Dreams turn to nightmares when she 'finds' the picture storybook, "The Babadook". This cheery little read would make Edward Gorey blanch. Think German expressionism meets Salem Lot's Kurt Barlow. This is the pop-up book you read at your peril.
Pros
Knockout performance from Essie Davis, clever art direction (those greys and drab blues dominate Amelia's house), fun collection of old movie clips during Amelia's sleep-deprived TV time (e.g. Bava's "Black Sabbath", film noir "The Strange Case of Martha Ives"), polished direction by Jennifer Kent, its economic length (under 90 minutes).
Cons
The final 15 minutes, while effective, resorts to some horror cliches/special effects. Oskar's baddie-busting gadgets were a bit "Home Alone".

Questions (contains spoilers)
Amelia was a writer years earlier (so did she write the book?). Why all the blank pages at the back of the book? Perhaps she should have written a happy ending to solve her problem.
Her husband's memories were kept in the cellar, as was the Babadook.
Why worms? Perhaps cockroaches, they certainly were more plentiful.
Amelia was deranged and still is (but containable, like our black cloaked friend)
The son became more normal as Amelia became more screwy.