User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-4632123-20150901213106/@comment-24834479-20150903222853

1. I personally don't think that Sam absorbed with demon blood would have been able to kill a knight of hell, but that is just my opinion.

2. Eves origin is not definite, but the most common thought is that she came from the Leviathan.

3. Even with the power of the souls, he wouldn't have been able to get rid of that part of his soul.

4. Sam was able to resist becoming a demon, but if he stayed longer, he probably would have turned.

5. Yes, the knights of hell were created by the power of the mark. I think the reason that Lilith didn't turn into a knight, because Lucifer didn't use the mark to create her.