The mirrored wall certainly gives you a 'wow' factor and the floor is stunning. I wouldn't do a textured wall paper or metallic, I think you'd end up with too much going on in a small space. If anything I would perhaps paint the white wall in a very light grey to pick up the grout in the floor tiles.

My vote is for matte as well. Especially in the bathroom. If the tiles are near the shower, the glossy ones seem to lose their shine to the soap scum and need constant cleaning like glass screens, whereas it doesn't seem to happen on the matte tiles which are quite easy to clean. The stove and the sink are really the only places needing a spashback in the kitchen and my vote would be for matte finish there, even if you use the same tiles in gloss every where else.

The period and style of your home suggests gravel as the medium of use. Grey, not blue and fine. Some products have clay 'fines' amongst the small gravel that enables the product to compact really well when laid properly. You can push prams etc over it without a problem. Paving and concrete cause drainage problems with runoff warranting drainage to accommodate excessive run off. Gravel and aggregates absorb the water. The cost is much cheaper but also looks totally better. The sustainable alternative is always about thinking differently.

Looks like the same tiles we used on our bathroom floors, a few walls, pool coping etc