Watch the ridiculous and hilarious "Dear Sister" here.
And the full song "Hide and Seek" by Imogen Heap is here.
Wonderful Ben, upon listening to the early release of the episode available to our upper-tier patrons, set the record straight on the Death Eaters. There are in fact three in addition to the Amycus, Alecto, and Carrow.
Here's "One Last Time" (by the way, these Animatic videos are wonderful):
And finally, per Pottermore, Tonks's patronus changed to a wolf to match Lupin's (not a werewolf)