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.

The hearth is more scraped than scratched. I’ll try some kind of buffing compound. Thanks.

Hardwood floors and classic brick. You can do just about anything that meets code. What about a slab of bluestone?

IMO you need to ask the flooring installers about what works best . DO you need a hearth ? I can't tell if this is wood burning or gas . Where I live gas does not require a hearth .From what I see at the FP just do a Tee mold in the flooring wood. As for the slate schluter makes metal ones that are almost invisible for 2 materials the same height .