In my limited experience, they will also go on strike when molting. Don't worry though, they'll go back to work again after a couple months or so.
We let them slow down naturally. Am thinking they will live longer and produce better when laying--am I incorrect in my "thunkin"?
I don't know, but the hens do look healthier (more weight, better quality feathers) since the days got shorter, so I'd bet you're right.
I keep a light on to make at least 12 hours light a day and have for four years. As far as I can tell it has not affected the health or laying.