I like the concrete bloc walls. They are becoming quite fashionable today. I'd keep them in the natural concrete color or if they have been painted, a color paint that resembles concrete. The concrete walls give a hard and cold impression so I'd choose wood flooring for the floors. The combination of a warm wood on the floor and hard, cold concrete on the walls is a nice one. Brighten the space with colorful modern art.

As the appearance of the garden has a modernist style with the straight lines and concrete furniture how about a Mondrian influence and add a bold strip of blue? It is a pond and with the right shade it could look really relaxed and contemporary. My daughter's suggestion is a chalky lilac!

I like the idea of patching over some green, especially if it is an investment property. 5 car spaces would be ideal in NZ.

I agree that you should take down the trellis but be aware that you'll probably need to extend your decking rail along that side in order to enclose the deck for building code purposes. If that's more of an expense than you're willing to incur right now, consider at least taking it down to the same height as the rest of your deck and putting a top railing across it. You could then put in some foundation plantings that would climb up and cover the fact that it runs in a different direction than the front of your deck. If I'm looking at it correctly, your gate gives you access to your front door from your drive way. Am I right? In that case, I think your gate should stay where it is. I agree with flair lighting that a new light is in order over your entry. If you like the idea of a motion light, they make decorative outdoor fixtures with motion lights built in. Your fence would definitely look nice painted a lighter color. Right now, as flair said, it's a bit unwelcoming. If you're painting your metal roof, take your house and trim colors from there to coordinate. You could definitely paint your scalloped trim a different color than the house. Matching it to whatever trim color you choose would look great. Do you use the steps from your deck to access your yard? If not, I would consider removing them and closing in that portion of the deck as well. If you do use them, I would add a hand rail for safety purposes. Congratulations on your new house and good luck with your project!