I agree that terracing is the way to go. Try and look at some picture online of Italian gardens. They use a lot of terracing in places like cinque terre and the tuscan regions. It might help to get a pro for the privacy landscaping or try to find varieties of flowering trees with will grow tall instead of full. Stone or possibly even tinted concrete (if on a tight budget) are easy are and should last a while. You can use potted plants and even potted fruits and vegetables. The best thing about potted plants is you can move them around and get a different look when you want a quick change, also fewer weeds and if you need to do anything to them like re-pot you can place them on a table to do it which is easier on the lower back than a traditional garden.

Id have Raised planter boxes put in around the outside of our yard so my mother in-law doesn't have to spend hours on the ground with a bad back to do the gardening!..

Check out www.clearpond.com.au Natural swimming pools need maitenance just like chlorinated ones. Just like chlorinated pools, once the balance is OK they are healthier than chlorine, especially for those with ear or skin issues. Its like swimming in a healthy river. Natural swim ponds incorporate biological filtration which is a natural process and Ultra Violet units for clarification and sterilisation.

I notice you have an aluminium screen door. Are the window frames aluminium as well? If so, you can re-paint them using a bonding substance called ESP. This is a link to Bunnings spray version but it also comes in a liquid you can wipe on and off: https://www.bunnings.com.au/flood-300g-esp-surface-prep-spray_p1560212 It's pretty easy once you get used to removing the screen and re-installing it (makes overpainting go away). It means that the paint won't chip off if someone knocks it which usually happens with aluminium and some other surfaces. Answering your questions, if you make the entrance lighter you may not need to make the walls either side lighter. I like dark - it is very dramatic and not as common. If you start with the entrance you can stand back and look at how it goes with the other walls. Also remember they don't all have to be the same. Variation in colour and texture adds interest, just make sure it doesn't look too busy and all the surfaces blend (not necessarily match). Your back wall is plain and straight, so regardless of the colour you end up choosing it will need to be augmented with something. You could try a large mirror on the blank space between windows. Something with a chunky frame in a contrasting colour and you will have a reflection of the greenery opposite. You could also try a reclaimed timber feature or something rusty or possibly a small timber pergola over the back door (similar colour to the window frames) that will give some depth. It's only paint, so try using patches with sample pots before you put too much effort into painting all the walls. Good luck.