The grey background you're seeing is an ad format that allows us to increase your number of impressions and revenue. It's becoming increasingly common practice, and while we can turn it off I'd definitely recommend against it, particularly as we're about to hit black Friday, and the best days of the year for global ad rates.
I'm also unable to find an example of the off-centre ad that you're seeing but if you can send me a url where I can find it I'd be happy to take a closer look.