I am outside at the main door. Last night after watching a youtube video of someone entering the temple, I noticed when they reached the door it said something like "door locked. open (e) key." My game says something like "door locked. open (e) lockpick.", but I have verified that I possess the key. I tried placing the key in different squares in my inventory but that did not work.

Regarding the three slayers. I defeated them all--well I think. It was a difficult combat for me and each slayer took a lot of time to defeat and I could only account for killing two of them. When I looked for the third, he could not be found, but I had a creature with me and I figured he killed the third. I could never verify this. It is possible he 'slipped' through a crack in the floor or something.

Your advice gives me new hope. I will first try going to the fjords and if that doesn't work I will try to reload, but that unfortunately would mean that I would loose a few levels and have to reconquer half of the Broken Valley again.