And the seating areas are different, don't try to make it look like one area. I would put minimal ( if any) teal around the black sofa. Do your dining room. Then give you living room the same respect, it is it's own space

Get the professional sander guys in to repair the living areas and kitchen but don't go too dark with the stain as it will kill the lovely grain in the matai. I'm thinking a couple of tones richer than the timber knots showing in your photo, definitely no yellow tone at all. In NZ stepping on to carpet especially in a kiwi winter is so much nicer than a cold floor board shock!!! A nice area rug for the lounge and you're done.

You are so right white is never out of fashion. I would set your budget and then look at your options. If you plan to stay in the house for many years then spend to the top of your budget (if that is going to give you a life time of pleasure), if you plan on being at the home for only a short time / few years then I would go mid range so it looks lovely, will have good resale value but you can invest your well earned money to go towards something else as well. Obviously Marble / Granite is the top of the range but there are so many cheaper and very attractive options these days that look just as good.

I would look at colour samples next to actual sample of the schist to be used. Take that to a local paint/render shop and look at them together. Looking at your image, the schist looks to be a golden schist rather than a grey. Is this just the way it has been shown? I would check with the suppliers for the actual colour of stone to be used as there are a lot of possibilities and the colour will affect your colour choice for the plaster. Here are a few websites showing some schist colours: https://www.worldofstone.co.nz/stone-mason/stone-masonry/schist https://wanakastone.co.nz/style/ Also consider the visibility of your mortar and its colour. Keep in mind that depending on your render system, you may be even more restricted in LRV, as some systems require an LRV of no less than 40%.