May I suggest that you look up the NCC Volume 2 which specifies the safety design parameters for stairs and balustrades. Any new work done on stairs and balustrades must comply with the code. You need to look up sections 3.9.1 and 3.9.2 In summary, whatever method you look to you can't be able to pass a 125mm sphere through any part of the stair or balustrade. It also specifies the design parameters for wire balustrades to achieve the 125mm sphere rule. The design challenges for stairs are significant if you want the open back tread look. The easiest way is to install a block on the underside of the tread level with the back edge of the tread below. This way you can still have an open tread and achieve compliance. The harder problem occurs when using a wire balustrade and the resolving the gap that occurs between the treads and the lowest wire. I have seen several installations of late where the 125mm rule was very clearly not achieved. One was a very recent build and I'm still not sure how it passed the final inspection. The images from Miami Stainless show how this can be achieved. Clearly the best and most secure is the glass balustrade and the vertical bar balustrade. Good luck!

You would have to ask SCA. I believe the gable roofs are for council (streets-cape). The cladding being corrugated, cost (pre-finished) and proximity to the coast (durability).

Yesterday I answered poring in the discussion instead of in the comment section Anyway, I can see there are new answers with very good ideas with lights Thank you

Here's the original discussion ([https://www.houzz.com.au/discussions/help-with-stairs-dsvw-vd~5209387[(https://www.houzz.com.au/discussions/help-with-stairs-dsvw-vd~5209387)) for context.