Are both sentences OK?
Nobody was surprised as much as I was.
I am surprised as much as you are.

Question

Answer

Nobody was as surprised as I was.
I am as surprised as you are.

These two examples sound more natural to me as a native speaker.

Answer

Yes, they are both fine. A couple of alternatives are:
Nobody was as surprised as me/ I was
I am (just) as surprised as you (are)

Answer

first one it's not correct sentence but the second is correct 
because surprised it's instantaly in the past you don't need to use "was"