Activate/Deactivate Static Objects etc.

[mansarde]

Will I need to put the .ent file into my custom_stories folder when letting other people play the map?

I haven't played around with custom stories yet, but I guess you will have to do exactly that. The only alternative is to let them extract your custom entities to their own entities folder.

EDIT:
Did you read this already? -> http://hpl2.frictionalgames.com/amnesia:custom_story
It's not explicitly indicated there, but from the folder structure they are talking about there I think you are supposed to create a similar folder structure in your custom story like in the "redist" folder.
I.e. I think you can just create a subfolder inside your custom story folder calles "entities" and put your custom entities in there (in subfolders themselves of course). Just try it out and see what works.^^