Concrete bench tops and decorative concrete pieces are a good idea if you like the solid look. I certainly would not recommend asking a general concreter about a concrete bench for your kitchen. Normally the bad rap that concrete bench tops get are when they are manufactured like a driveway or footpath. Kitchen bench tops require different characteristics. They should be constructed dense (to help prevent staining), flexible (to prevent cracking), lightweight (so can be manufactured off-site). With the materials that are available now, concrete can have all these characteristics. Sealing is another topic for the professionals. There are three different methods of sealing concrete. Penetrating, Topical, or Reactive. Sometimes all three are used to seal a concrete kitchen bench. This is because the way a kitchen bench is used is different to a floor. You are not only trying to prevent staining, you are trying to prevent etching that could occur with acidic foods. There are companies around that specialise in concrete bench tops for kitchens. Try them you may be surprised at the options available for "concrete" bench tops.

This is going to come down to what your space is like, light, how you use the kitchen, how does it relate to other areas of the house ie. is it open plan, so needs to complement other areas such as dining & family? Here are a few examples of backsplashes with concrete benchtops. Depends on your personal style & taste as to what appeals to you. My 1st reaction was marble, it would give interest & movement but without knowing what else you have going on in the room...

White-matte cabinets (flat panel, not shaker) and white bench (or maybe epoxy sealed marine ply??...siriuskey can tell you about that), mirror splash. Love the ceilings. I personally would go for a modern, stream-line, no handles, integrated appliances look. This space has real potential to be very cool, even with the slate. It doesn't need any more more texture or darkness. This is a nice kitchen, you should be able to sell it on ebay.

In the general care section of the Bettastone site it says "All Betta stone products/slabs should be stored under cover away from harsh weather" It also carries a lot of care warnings so if you go that direction I would suggest asking them direct if their product is first Fit-For-Purpose. Caesarstone say their range is UV resistant now, so this is now an option. Natural Granite has always been an option, as too is Stainless Steel, as well as Corian Solid Surface and as already said above Sheet Porcelain (i.e. man made Sintered Stone materials such as Neolith and Dekton) can be used. Hope this helps, Malcolm.