Floating ground applied only to the Mk.1 player, which finished shipping around the end of last year. Don't worry about that - treat your Mk.2 just like you would any other line-level head unit.

As for grounding, there are many different ways - including running (thick) cables direct to the battery. If you can get a good ground from the chassis then that's usually fine, but the problem comes if there is a slight potential between the amp ground and the head ground. In general I advise trying the more straightforward techniques first, and only worrying about more complex installation methods if you need to (some cars are easier than others!).

If you do have any problems there's a wealth of knowledge and experience on here to help you out, or consider talking with a pro installer.

Rob