It must depend what you cook. I don't do fried, spitty type dishes and the grout around the largish tiles in my now 10 year old kitchen is as good as new. I rubbed car wax into the freshly laid grout lines, same as I did in the bathroom. It also depends on how much light bounces around your kitchen, glass being so reflective shows up smears with light on it. Just above the kettle in the first photo is a good example. Each to their own, I'm a non-glass girl whenever I can get away with it.

Hmm, 200mm diameter is about the size of a side plate, 300mm dinner plate and after a quick look at a few sink brands (eg Clark they seem to all be closer to 400mm). I did comea Cross this one but have no idea of the brand quality http://www.swanstreet.com.au/CM1-Undermount-Single-Bowl-6L-Small-Bar-Sink-330-x-200-x-125mm~3600

based on available dimensions i suggest that side by side semi recessed basins in twin shallow vanities will be more comfortable than squeezing through the tiny space leftover with vanities on opposite walls, my curve may not be precise but i suggest that a 1200 x 900 fibreglass shower stall with sliding glass doors would solve the problem of waterproofing and allow for a shower door that would not need to crash into the vanities and the small section of glass bricks visible would not be affected by direct water spray,,, the wall next to the window should be sufficient for a mirror doored wall cabinet and the wall around the bath and next to the door will allow space for towel rails and the laundry basket and installing the (standard 820 wide) cavity sliding door to open towards the bath will be less work as it will use the existing doorway ...if you decide to use the void behind part of the glass brick wall painting the glass white? from the bathroom side could make the view from the stairs more attractive

There are indeed building code safety requirements that govern the design of balustrades, including the gaps around panels. Sometimes compliant gaps at the maximum opening look a bit off. I find that smaller gaps, 20 - 50 mm often look more pleasing. You say your patio is not covered. In that case there is little potential for any balustrade to trap heat. An uncovered north facing tiled patio will be a heat sink, and a glass (or substantially open) balustrade will allow more sunlight onto the tiles which will increase heat gain. A solid balustrade may reduce that heat gain due to it's shading potential, but I am guessing you want glass for the view, so if heat is a problem, consider adding a roof covering to shade the patio.