I think you can very well still have plants in a windowless room- as long as you're willing to give them regular little 'windowsill holidays' in another room. I'd go with succulents, there are some great warm colour combos (see Pinterest for ideas) and the geometric shapes mimic your tiles. Of course, there are some incredible fake ones around too, saw one last week I could not pick from the real thing. I'd be tempted to mix in some of both to balance aesthetics with practicality! Separately, I'd be careful of adding any soft furnishings (rugs, spare towels, etc) to a small powder room. We are all aware these days that a flushed loo spreads germs a meter around it- I wouldn't want to be collecting and trapping them! I think (subtle) fragrance and votives would warm this lovely space without impeding hygiene.

I love the timber panelling, maybe with a bit of a clean it will look a bit lighter, but in any case, I love it! I actually think some lighter flooring would make the room work better - not what you were asking about I know! The current flooring being dark and matte sucks a lot of the light out of the room and also makes the timber panelling/fireplace feel heavier. Even a lighter rug (or even a fun Ikea Stockholm rug?) could make it look more crisp, fresh and stylish, whilst still giving a nod to your home's gorgeous retro features. A fresher light fitting - maybe a simple drum style?) would make it look more modern also and less busy to allow the original features to be the focus. Your existing armchair etc suit it beautifully though! The fireplace I'm not sure about - I hate to ruin original features but I'm not sure about that?! Maybe wiht the other changes done it might work much better anyway? Otherwise an interesting tile or sandstone cladding could work beautifully with the timber tones?

And change the light . That room will always look 1970's until you change it IMO . The new layout looks approx 1831% better IMO haha . A big ( at least 1.2mtr long by 800 tall ) abstract picture in bright reds , oranges , yellows with a bit of green and charcoal would add some colour . So would a red rug . Yellow cushions . Some colour in other words . I've never done it , but possibly even look into dying the blinds -- a mid yellow or even a brown may lift the room , but be subtle enough to not overpower it ? If you want to go more into blue or green tones for the whole room , you probably could , but you'd need to get rid of the black couches .

You could try Wet & Forget on the driveway. You can buy it ready to use and attach it to a hose or buy a bottle that you dilute to use in a sprayer. I have used it and it works - slower than water blasting but it won’t damage driveway if it has some damage? I can’t quite tell from photo if that’s grass clippings/mulch or broken concrete on driveway? If you use it be careful not to spray garden bed. I live in FNQ and we planted seaside daisy - doesn’t need watering but it also won’t die from our wet season. It’s a ground over and spreads out beautifully in a courtyard area that’s get a lot of sun. Just needs a trim from time to time. I see you have Rio (purple green ground cover) which you could separate and plant down the path but it does like water. Maybe for the fence you could try attaching lattice to it and plant another passion fruit vine to help cover the whole fence. It does look like you need to get rid of some woody parts of the passion fruit. It’s a tough plant and will enjoy a bit of pruning. We had one that I thought had died last year and it has returned with no help from me. Be careful with the heliconias and gingers ... they can get out of control if you don’t stay on top of them. Anything tall will cover your fence but it will also cover the passionfruit vine which obviously loves the spot it’s in. Good luck!