Why Automatic App Updates In Market Don't Work? Every time i see a few of apps trying to auto-update themselves but just stalling when it says "Downloading". In other words, automatic update for apps does not work and I am only left with cancelling download/update and doing this manually.

Is there a reason why automatic updates do not work?

Additionally it would be good to know if there was a way to schedule updating of apps or somehow to update a few at one time because updating many/most apps after accessing internet after a long period of time just bogs down system.
This can happen if the download cache is full or nearly full, and the download would fill your internal storage.  Try cleaning out your caches to free up some space (SD Maid is a good free app for this) and seeing if the downloads will complete then.