User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-27006668-20151026175427/@comment-24834479-20151026235142

1. They were able to hold on inside of Castiel.

2. Because that's how she was made?

3. Left for interpratation

4. No

5. If you mean stronger, than Leviathans, but I personally like the Angels better.