Hi Zara, me again. If the tiles are all cracking, there probably are air bubbles in the mortar underneath. Taking it all out is the best choice you can make. Like I've said in your other posts, taking only the broken ones out, will take more time and effort than replacing all of it. On top of that, when it's bad underneath, you can just wait for the next tiles to crack. Wish you well.

I think the roof might be a bit too dark for the brick colour. The bricks and the window joinery will blend in fine. What did you decide to do?

How about some stunning black wall sconce lights along the wall? Here's a very contemporary example... The soft grey is an excellent option, and will look stunning with green foliage against it. To give it a real 'look' I'd suggest installing some kind of black feature - whether this be painting the window frame & putting shutters either side, or the sconce lights, or a modern metal artwork. Perhaps even tall black plant pots either side of the window.

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%.