Another update for you although small. Game.co.uk have chnaged the Artwork and image of each editions. they say they are not final but promo only, but I would say they are close to the final finish.
Epic Edition:
And the
Limited Edition
If these are the final images, they it looks like they the planning on having a similar situation of Halo Reach, the large one could have a figurine or maybe even collection of characters. Can't imagine a replica gun, not at £99 anyway.