Hey there. While I don't necessarily fulfill all of the qualities you require (I have little knowledge of Amnesia mapping) I do have experience with mapping in general, and am an excellent bug tester. I can also provide proofreading; correcting any mistakes I find in the custom story's .lang files. All the bugs I encounter will be documented with screenshots along with corresponding text and will be delivered in an easy to read report (corrected .lang files included, to be used if you so desire.)
I have a thread advertising my bugtesting/proofreading service, and I asked a few of the people whose stories I have worked on in the past to post their opinions of me there. I take my work very seriously, and I hope I can help provide you with a better product when it's ready to launch.
You can see the thread here:
http://www.frictionalgames.com/forum/thread-14327.html
If you're interested, just shoot me a PM here, or you can add me on Skype (summakore@gmail.com).