A ledger is a board that is secured just below the counter into the studs. It should be 2" deep by 1" high at a minimum. I have a dishwasher that has granite over it with cabinets on either side and my contractor installed a ledger. You will need to have the panels on either side because that is how the dishwasher gets secured. I learned this the hard way. We reused our dishwasher and it was not designed for securing below granite. They put screws into the sides of the cabinets but the dishwasher went out of square and leaked water all over my wood floor. Fortunately most of the water ran into the basement below and my 90 year old floors weren't ruined. We ended up purchasing a new dishwasher designed to be side mounted. But you definitely need something to attach it to.

If granite really caused cancer, you'd hear it all over and not just from some guy at work! The many other options are lovely and you should consider everything before you decide what feels right. Luckily, you can see good examples of almost every kind of counter in the finished kitchens blog. You can also find out info about any surface by reading here and asking. Try the search function to see other threads like this. I am sure you will be busy reading for a while, lol...

WARNING: My analysis could be considered biased. I've been in the countertop industry and, specifically stone countertops, for almost 15 years. Various people and industry trade groups have been predicting the demise of granite for most of that time. They were wrong then and they are wrong now. In that 15 years lower raw material prices and substantial reductions in fabrication labor have made inexpensive granites cost competitive with everything but laminate. Concurrently, large numbers of new more exotic stones have come to market giving the consumer and designer far more options helping to sustain the up scale characteristic historically associated with natural stone. There is a reason why the most successful quartz colors are the ones that come closest to the movement and colors of natural stone. Unfortunately for the quartz lovers the knock-off colors fare very poorly when compared side by side to the actual stone being copied. Additionally, the consumer is becoming ever more educated and less susceptible aggressive marketing by the manufacturers of competing materials. Consumers have learned that the various derogatory claims about natural stone (staining, radon, mold, etc.) promulgated by competitors are untrue or vastly exaggerated. Natural stone will be around for the forseeable future. Artificial countertop materials will likely exhibit the normal manufactured product life cycle and end up as desirable as the rayon leisure suits and shag carpeting of the 70's.

I have a light countertop with my wood cabinet, but with your backsplash I think the darker one would look very nice. Sometime the backsplash will get damaged when removing the countertop or the new countertop is a different thickness causing a gap. Be sure to discuss this with your countertop person. You will have more options if you change the backsplash too, but there is no need to if your countertop place can make the present one work.