White-matte cabinets (flat panel, not shaker) and white bench (or maybe epoxy sealed marine ply??...siriuskey can tell you about that), mirror splash. Love the ceilings. I personally would go for a modern, stream-line, no handles, integrated appliances look. This space has real potential to be very cool, even with the slate. It doesn't need any more more texture or darkness. This is a nice kitchen, you should be able to sell it on ebay.

I just googled & found this site, which quotes cost of R2.5 75mm. there are other suppliers as well. What was quoted to you for cost of roof installation, and was it itemised so you can see exactly what thickness the foil-backed insulation builder will use? I'm guessing the thinner (lower R factor). So, the new quote should reflect a credit for the cost of previous insulation, since it won't be used, then cost of thicker insulation added. Does that make sense? If you are unsure, best to speak with the builder. https://www.pricewiseinsulation.com.au/product/heavy-duty-fletcher-permastop/

I agree with Jan -- a lot is personal , and your lifestyles . You say neutral colours , so a wheat type colour for the carpet is a good middle of the road choice , but maybe not practical with kids who like crayons and facepainting and stripping down motorbikes haha . So in that case , maybe a burgundy or mid blue or similar 'solid' colour may suit better ( burgundy may tie in more with the exterior tones ) , but is still sort of neutral , but what about furniture and linen and artwork -- if you have royal blue or fluro green drawers and a brown chair and sunshine yellow duvet/dooner cover , and the room is for someone older than 4 , then burgundy carpet mightn't be the go haha . The existing wall colour works with most things , you can add artwork or posters or sports or academic certificates -- maybe back to front , but I'd sort out everything else ( carpet , furniture , etc ) before deciding on a wall colour , unless sticking to the existing or similar colour .

2 pac paint has the advantage of custom colour selection, and i would say thisnos the only advantage it has over other finishes.