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/

consider a similar colour in a shade darker than the timber trims...if the plinth is exposed to nearby lawn mowing or garden beds the darker colour is more forgiving of dirty marks and makes a better background for planting

Paint swatches are your friend here, either sample pots or the A4 size that Dulux introduced. Paint looks different in different lighting and surroundings. Our, barest touch of blue, interior paint, has one wall that throws a bit grey in certain light - the one thing I was trying to avoid - but is perfect everywhere else 🤷🏻‍♀️ . The initial favourite, while the paint chip was very similar seemed over saturated. It’s definitely worth a visit to the paint specialty stores, many have colour consultants, if you’re still undecided. We also found them less expensive, too.

I quite like it as it is. I assume the will be a fence to the north of office to create yard where clothesline is. Your frontage is really all garage given the court bowl limitation. Dark as shown on the eastern side which is mainly garage shouldn’t be a problem and help recess the garage. You will need to landscape to guide and entice people to find your front door as it won’t be visible from street. I would prob have a gated entry for security.