There are many examples on houzz of contrasting counters for perimeter and island. For example butcher block on island and stone on perimeter or a solid color on one and something with movement on another. I would only mix two stones if one had movement and one was fairly solid. The stainless on perimeter and something else on island sounds good to me. Here is a pic of stainless counters with what looks like a stone breakfast bar. (I hope I understood your question right). http://houzz.com/photos/3137660

Either will be nice, especially with a speckle through it, the black will be more dramatic, it depends what suits you the most, I myself would go for black as I like contrast and I'm a bit of a drama queen lol

If you have bare walls, then choose colours that won't clash and would tie in wiht the room. Then pick out colours you actually like and pick a favourite. Most everything will go with Grey but contrast is usually more visually pleasing.

You are so right white is never out of fashion. I would set your budget and then look at your options. If you plan to stay in the house for many years then spend to the top of your budget (if that is going to give you a life time of pleasure), if you plan on being at the home for only a short time / few years then I would go mid range so it looks lovely, will have good resale value but you can invest your well earned money to go towards something else as well. Obviously Marble / Granite is the top of the range but there are so many cheaper and very attractive options these days that look just as good.