a) I'm not the author so can't comment on what they really expect. But since they released the work under CC I'd suggest nothing, other than recognition, and based on the post after they finally realised their true reason for being hurt, I think it was also about being treated correctly and with respect.
b) INAL, but in the UK: "you automatically get copyright protection when you create: original literary, dramatic, musical and artistic work, including illustration and photography original non-literary written work... ". Assuming it's similar around the world there's nothing dubious about their claim, they didn't sign it away.
Regardless of your opinion of the person or their motives it seems they are within their rights to do what they've done.
b) INAL, but in the UK: "you automatically get copyright protection when you create: original literary, dramatic, musical and artistic work, including illustration and photography original non-literary written work... ". Assuming it's similar around the world there's nothing dubious about their claim, they didn't sign it away.
Regardless of your opinion of the person or their motives it seems they are within their rights to do what they've done.