What happens if i have preordered Skyrim off the interent and it comes a few days early, which does occur quite often, will i be able to play or will i have to wait for the steam release date to be able to play it because it will still be locked?

Release date, as it unlocks right at 11-11-11 @ midnight

I think you'll have to wait until Steam gives you the all clear to play it

I thought that'd be the case Grrrr... midnight playing it is then

Can I install from the disc i.e. The Orange Box? I'm assuming I'll be able to.

On the upside you'll get to pre-load, and start as soon as it unlocks. Unlike we console players who buy the game at that time if were lucky.