Ok, question 2, is your P5 up to date? I personally hated P5 and skipped over to P6. Do you have ANY detached nodes in the material room? P5/6 also freak out sometimes if there are lost nodes that need to be deleted. (P6 has a button to clean it up, P5 dosent) (I think it doesnt)

I came, I rendered, I'm still broke.