Hopefully I'll have some time later to ellaborate, but for now - this here is a great reference I wish somebody had shown me when I started out, for how to attack questions of this type: http://books.google.com/books?id=l0DgAIx_djoC&printsec=frontcover&dq=waterhouse+affine&source=bl&ots=nup7qU4Aln&sig=VXgsPcQNgAkCbNsH8KG-VAakjio&hl=en
look at chapter 17 (and 18).

