hmm, im not totally sure what key your refering too, but... (um, i don't think its much of a Spoiler, so i wont mark it as one lol)
if you mean the key to get through the main gates then just convince the guard to open them (no key needed) and...
if you mean inside the castle then the key is in a chest (with a note id advise u read [img]smile.gif[/img] ) Hope this helps [img]smile.gif[/img]
As to your AC, um, your a monk so its not much of a surprise that you have a low AC (being as you probably dont have much armour [img]smile.gif[/img] ) but to get your AC up, just buy some AC raising items, such as a necklace of natural armour, or a ring/cloak of protection (but remember that some AC bonuses wont work together, so you cant wear a cloak of Protection and ring of Protection together and get both the bonuses, you just get the higher one). If this doesnt make much sense just read the manual, I think that explains it a bit better lol