Plain ceiling white is a good choice for ceilings. I'm a huge Natural White fan but will consider Whisper White next time I'm painting.

I agree that it's hard to choose the style without seeing the rest of the house but that a charcoal colour (same as the island cupboards) would tie in best with the colour scheme you have. Depending on the look of the house you have a lot of options to choose from and a lot depends on personal taste or budget. Glass is easy to keep clean and is a modern look if you are not wanting to draw attention to the splashback. Mirror (plain - modern or distressed - character) is lovely if you have something nice reflected in it. If the kitchen is messy though, it doubles the mess. Subway tiles (regular or irregular, tiled in brick format or herringbone) are always a lovely classic choice - but be mindful of grout issues. Arabesque or patterned tiles add more character if you're after tiles with a wow factor. I personally love stone, marble or quartz for an elegant, timeless look and in a charcoal or grey with veins I think would look stunning with the lamps as well as tying in the white and grey cabinetry. You can also do marble tiles that are a little less exxy than a slab although in the end I was surprised that the marble didn't cost much more than the caesarstone. Choices, choices!! Good luck. Your kitchen looks lovely!

Really hard to tell. I like the lightest one but I'm not very adventurous. You may need to choose one and paint a larger area and see what you think.

You can’t go wrong with white. I always suggest match to the wall colour or the trim colour.