There are tons of papers available that would go with your midcentury home. Many people tire of a paper quicker than they are ready to redecorate and they can also look dated in a couple of years. Metallic papers were big im midcentury...perhaps a metallic silver paper? Are you also considering paint? You can get it in so many textures and a blue wall to match the blue in your loveseat would be lovely with some midcentury art and sculpture, or photographs on it. A mirrored wall with or without art or sculpture would also work with midcentury. These treatments are easier to adapt should you wish to change the look slightly from time to time. I would suggest replacing your stairrail with chrome or acrylic if that is in the budget...see how well the loveseat frame looks with the fabric? I hope you will post the "after" photos for us to see. Above all, enjoy the process!

Have you tried Googling "topiary trimming guide" or another similar search phrase? You might run across what you are looking for that way.

Not yet - I am thinking I will get a length of aluminium angle and put that on, or else a piece of timer and then paint it with waterproof paint.

As chookchook said in her recommendation about painting, put a drop cloth on the floor. Get a very safe ladder. remove the lightbulbs, and cover the outlets. Turn off the electricity to the chandelier. Then spray it with a mild cleaner (I use one I found at Target that's basically water with vinegar, until it's dripping wet. Start at the bottom and work your way up, so you don't have dirty spray dripping on the bottom of the chandelier.Work your way up and down until the dripping spray is clean. The chandelier may be gorgeous and expensive, but it seems totally out of place in the architecture of the room--more at home in a chalet than a sunny room with a window wall. I would probably try to find a way to get it removed, and sell it to someone who appreciated it better than I.