Put a towel in bottom of bathtub, place oven rack with pizza stone on the towel and cover with hot water. Allow to soak for a while or until you can remove the stone. There may have been sugar or other kinds of drips on the oven racks that fused the pizza stone to it. Water will soften the drips allowing the stone to release. Be sure and let pizza stone dry completely before using.

You need a chelating agent for rust, namely oxalic acid. You can buy oxalic acid crystals where paints are sold (it's usually used as a wood bleach), or look for it on the label as an ingredient in products sold for rust stain removal, like Zud or Whink. Because stone is porous, it's always a good idea to use a poultice when removing a stain, to draw the stain up and out, instead of dissolving it deeper into the stone. Home centers sell clay powders for use as a poultice (look in the tile section), or just use corn starch. Mix some oxalic acid crystals, or the cleaning product containing the acid, with the poultice powder (say about 50/50) and enough water to form a thick paste. Apply the paste to the stain, let it dry, and vaccuum up the dried poultice. You may have to repeat this several times. The oxalic acid chemically converts and dissolves the rust, and the poultice absorbs and removes it from the stone.

I actually designed the wall and hearth and had a local brick mason do the brick work a few years after we moved into our new home. It wasn't part of the original room. I know we used cinder block under the brick to build it up so I already know what supports it. However since it was about 30 years ago, I can't remember how else we finished the support system. When we relocated the wood stove to the family room, I was very happy to see the big black stove pipe that went from the top of the wood stove through the ceiling removed. I thought it detracted from the overall appearance. I prefer to keep the height of the hearth the same since the grandkids like to sit on it. Another issue is since the hearth is raised, I don't know how we could join a lower hearth or floor to the back wall since the wall brick starts off the hearth, not the floor. But I totally see and appreciate the idea that it would create more room, since a chair from the dinning table could be placed on the tile (or wood) flooring. Thanks for the suggestions and comments....I appreciate your time and expertise....:)

Your kitchen isn't actually possessed, it just has 2 neutrals from 2 different hue families. Trying to add a third hue is going to be difficult because anything that is close to the hue of the flooring will look too pink next to the countertops. Any thing close to the hue of the countertops will look green next to the floor, You could stay with white cabinets or use a navy blue or gray green.