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

We have Caesarstone in Misty Carrera on our island. It has a slight warm gray hue, which works well in our kitchen, and it's very durable against us and our kids.

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

Black and yellow are both very strong colour choices and I feel you'd be sick of them before it was time to change them. Black also shows marks more than you'd think. Clear is fine, but have you considered a piece of art behind clear?There are several companies that do this, imageglass.co.nz had one with tuis in it which has black and yellow. As for size are you having a range hood? If so this might affect your choice of size.