First off, great job so far!
The brick on the fireplace doesn't bother me either. You chose the right shade of blue to complement the orangey color in the brick. My only concern is if it's clashing with the floor color. It's hard to see from the image. However, if you want to make a more uniform look, then you could always paint it white. I would live with it for a while to feel it out to see if you love it in the end. You can always paint it down the road.
I really like the penny round backsplash idea from miacomet. It feel like it would add a bit of character to the room. I also like Mrskain's glass mosaic ideas as well... Keep it a nice neutral color and definitely go with a mosaic.
Hard to tell, but it looks like the pendants aren't centered above the peninsula. I would try to even it out. Don't go too large with your pendants. You'll probably want delicate and a nice medium sized pendant. You can take a look at some of our blown and fused glass pendants we make. We can custom make them as individual pendants, or make a single canopy that can center over your existing holes and still be centered over the peninsula (if it's an issue). I also feel 2 may look better than 3. We can also do a chandelier for the dining area that coordinates (not matches) back to the kitchen pendants.
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