To be honest, unless the dog was laying down most of the time,you may struggle with that. Plus with no proper divide between the cockpit and the boot, its probably very dangerous to have them there. Sorry hadnt thought of that in my original post.
As for miles, you can get around 400 out of a tank if its constant motorway, and id say probably 300 with mixed driving, and as little as 200 if your flat chat round a track,maybe less. I averaged 11mpg on one of my first track days.
You will find most cars have the GT pack, so that comes with leather and Bose sounds system. Though the latter sounds more appealing than the actual reality of having it. So dont be surprised to find alot of people change it, or hack it to add an ipod cable.