rnarchlord

Actually most of the keys do not disappear but remain in the quest items of the stash.  This also holds true for the notes in the sanitarium.  Five playthoughs and each ends with a mess of keys in stash.  

Did you go East through Black Meadows and exit on the East side?  That should have put you on the bridge directly in front of Caed Nua's entrance.  If you already killed Maerwald and took possession of Caed Nua did you repair the Eastern Barbican and go through it to Woodend Plains?  If you did then you can try clicking on Woodend Plains and exiting north to get to the Eastern Barbican entrance.

Northeast of the junction chamber is a room of glowing Adra and five
Animats with a Cean Gwla. Before leaving, inspect the Cracked Animat
Armor lying on the earth by the Adra crystals. It contains the final
element needed for Tcharek: Adra Shell. This shell should be collected
for Tcharek as part of the side quest. At this point, backtrack to Level 13,
speak to Tcharek, and conclude this side quest.

I use traps and AOE spells without a problem.  Use sneak/scout mode to get close to the mob and place traps.  Then have your party far enough back so the mob have to run through the traps to get to you.  Use one party member to sneak within bow range first and attack then run him back to the rest of the party.  If you walk him/her around/beside instead of through the traps when sneaking the party member won't try to disarm the traps and can run through them without triggering them getting back to the party.  This leaves your spellcasters able to throw AOE spells without getrting near the traps.  If you want a spellcaster to initiate the combat have them sneak carefully around/beside the trap then run her/him back to the party through trap you just set without problem.  If your cursor touches any trap it automatically goes into disarm mode so always click on safe ground when positioning party members.  Hope this helps.