What was i supposed to find in the Prison of Saradush. All I found was a lot of Vampires, and a Bronze Ioun Stone, so I'm assuming i'm missing something.

you need to go through the entrance to the sewers ;)

Uhh, if you got the key from the preistess, you should find a secret door in one of the cells.

I found two secret doors. One stays locked, and the other one i got open with the knock spell, and i still did not find any stairs or another type of entrance to the sewers.

There are two ways into and out of the prison. The first way is the way you came in, in the center of the prison. The other way leads to the castle dungeon. This is on the far left hand side. (It may be a hidden door, so try searching for them).

try to go as far left as possible..
you should meet a vampire that initiates a dialogue with u... right to its left is a region where you can click to go into the sewer under the palace...

also.. i think behind some of thsoe doors are vampires...