The driver will have to cut his way through the unmoveable plastic hatch on the roof of the turret
As to the hull being just a shell, nope. It just looks that way, there is a bottom half, it's just not visible on these pictures. When I've made progress I'll post pics from a better angle, with a miniature for scale.
For the game system question, the sci-fi wargame I'm most likely to play at any given time at the minute is 40K, so I assume it'll get a run out in one of my next 40K games. I did have a think about statting it for Skulldred but that's just a bit silly.
I've got a couple of unbuilt/unpainted GW Leman Russ tanks from years ago lying about and I'm thinking of using the same paint scheme on them. I've had an idea to build a sci-fi armoured cavalry force that could fit into the 40K setting but also be generic enough to exist outside it, if you get me.