I've attached what i mean with the wood grain
i hope it makes sense... i just quickly did it in paint

i think jsprogg explained what i meant to say about the shed

and tbh, i didn't actually notice there was fog you should just render it in a seperate layer and then just composite it on afterwards so all you will be rendering are the objects

and about the sky dome, i haven't got an answer because i never seen it before either... just heard about it, although i think ragecgi has one in his render layers tutorial but it's not the focus of it, so maybe you'll have to google 'sky dome tutorial' or something