I agree with everything said so far. Would suggest you get built in book shelvers on both sides of fireplace, lift tv into a slot it fits perfectly into (make sure you have power on both sides). Then it will disappear more rather than fight with fireplace as focal point. I am always disappointed with mirrors over fireplaces, they become dark, are to high to reflect much. Plus then you have three rectangles fighting for center stage. I'd say very colorful artwork instead. Wonder if you can reorient tv where the big chairs are so both tv and fireplace are addressed? Color, maybe you should decide on furniture first?

Start searching barn sales, antique stores. Could you post a photo? Could do plates. Could look for an old door.

You can stay neutral but use different textures in the tiles. Glass mixed with ceramic or marble is good. I would put tile on the entire backsplash and make a great accent piece over the range. Change up the patterns also. It will add interest without adding too much color. If you want to be bolder, chose one or two colors in the tiles that you can live with or that you have in the rest of the house. That will pull your color scheme into the kitchen and make a cohesive look as you go throughout the house.

Yes, it's great! Remember it's sealed the same way a gloss surface is sealed - or it should be! Make sure your installers give you a warranty for the sealer they apply - my installers offer 5 years. We recommend mild all purpose spray Green type cleaners - no bleach and no ammonia.