[Melondar]

ok, Ive gotten into the lower levels but I have 2 more questions:
First of all, I had to cast silence on Tolgerias and the other mage so it was a lot easier to kill them, but because I did that, I couldnt initiate the dialogue with them that would normally happen (since I casted it from an area where I couldnt see them.) Does doing this affect the game in any negative way at all?
Also, a second question: Ive gotten to the engine room and everything, put the heart in but there is another door in the room Tolgerias was in that is locked, I couldnt force it open, and couldnt find a key. Is there a key anywhere, and is there anything in there worth getting?