I think I can't do Houzz in the shower, and I'm not game to find out. To keep room cool without blocking the view (not the rays, you need to block them), I advise tinted window film or matchstick blinds. There are also new generation ray blocking blinds at places like Spotlight.

Shades/curtains closed from early in the morning! No using the oven!

I have ducted A/C through out the house..all the bedrooms have ceiling fans..the back bifolds have louvres roofing to protect from afternoon sun..also privacy screens to go in to add to the protection apartment is over insulated so we don't tend to turn on A/C that much ..just to cool it down then we turn it off

Hydronic slab heating is fairly straightforward to install and not that expensive compared with other forms of central heating. If you try to cool the slab, it becomes a lot more complicated. First up, cooling the slab does nothing to remove humidity from the air, which is a large part of what makes you feel hot. Second, you need some way of controlling the heat pump between heating and cooling mode. Usually we use mechanical thermostats which switch on when the house gets below the set temperature, but when you change to cooling mode it needs turn on when the indoor temperature is above the set temperature, so instead of a standard central heating thermostat you instead need an electronic temperature sensor. Anything is possible, but the short answer is that having a chilled slab will be more complicated and more expensive than an air conditioner, and less effective. You'll also need to find a contractor to design the system, and because it will be a custom design if you have any issues in the future you'll need to get the same person who installed it to come and fix it, which is a problem if they move, go on holiday, or close their business.