Having experienced a leaking shower, a step down sounds like a welcome added precaution, which seems rarely done. Supposedly if there is no hob or atepdown there is an angle, and obviously the whole thing is supposed to slope towards the drain anyway, but BeachBathrooms' earlier comment about capillary action rings true. It became obvious very quickly in our other shower that water was creeping across the grout outside the shower so whatever was meant to be done either wasn't or wasn't correctly done. Then there's the modern hotel bathrooms I've experienced where the water simply splashes out too easily. All in the name of style.

Love it as is. Well done. The void above living will let on light, just be careful of not letting in the western light too much. So some way to shade house on the backyard end. would be good.

I would suggest Luxury Vinyl Tiles, especially for a kitchen where the floor could get wet.

electric underfloor heating is great for bathrooms (and laundry, mudrooms, entry and hallways when it needs to be left on for weeks at a time and not much good for a ten minute shower) and is preferable to anything visible like hydronic heaters that take up wall space but your voids will suck most of the heat upstairs ..our reverse cycle AC has been much more economical to run than the whole floor electric slab heating that we had in our previous house (supplemented with a wood burner and gas log fire in our cold climate) but we made sure that the void over the stairs was able to be blocked off to zone heat downstairs with separate heating upstairs but having lived in different areas of Sydney i'm wondering why a new built well designed house with great insulation would need more than modest supplementary heating that can be more economically provided with AC