What was Kripke's plan?

Does anybody know some ideas that Eric had for Supernatural and decided to change them for this or that reason?

For example, I know that Anna was supposed to do some things that Cas did cause the fans liked Cas better then her.

Jessica was supposed to be evil or possesed.
The show was supposed to be about a journalist.
John was supposed to appear in DALDOM insted of Lisa etc.

Do you know anymore interesting stuff like that? Does anybody know the plans for Bela or Jo (if it wasn't for the fan hate)? How season 5 was supposed to end?

Thanks!