Caprica 6 and the other Baltar were angels but do you think Thrace was an angel or a ghost?
Thats the beauty of this series. Each fan can have his own interpretation of all the things that happened in the show. Others may not agree with ones interpretation but, what the heck, its just a show and I enjoyed it to the very end.
Now with the question, is Kara an angel or ghost? For me, I would like to think that she was neither. She was part of the plan of a higher Divine Being that somehow controls the destiny of everyone, cylon and human alike. Did she die in the crash? Was her DNA and memories extracted and transfered to another identical body in an identical ship capable of receiving beacon signals that other vipers cannot? We would never know but it could be the story arc of another mini series or BSG 2-hr special in the future. (or another set of webisodes)
Until then, I look forward to the release of the final boxed sets of BSG here in the Philippines.