White curtains or very pale grey will keep the light levels high in your room and make a nice backdrop to your furnishings. I think patterned curtains are more casual and with the amount of windows you have, they would make a huge statement in the room. Darker curtains will reduce the light and can make the room look dingy. If you felt you don't want perfectly plain fabric, look for a slub fabric or something with some interest or texture in the weave. You could even have a self stripe which can look very elegant. I have just finished new curtains through my house and did the double track where I could and used a thermal lining that I can pull across to keep the cold out and it worked very well and is also working well now in the heat keeping the rooms cooler - in fact it is amazing some days the amount of heat trapped between the curtains and the windows and kept out of the room. In my bedroom I used a heavy sheer curtain to be able to enjoy the view of the garden while still maintaining privacy and the thermal lining gives me full privacy at night. I'm thinking this could be nice for your room when you have such a lovely outlook too and you do need something to keep the sun off your furniture and furnishings. There are also thermal roller blinds you could use instead of curtain linings, these do darken the room but they work very well. If you use the linings though, there are different weights, I used one pass in my bedroom and other rooms, and it does not darken the room very much at all. In my lounge room where I really needed heat blockout in summer, it was a bit of trial and error - I used triple pass and it does significantly darken the room to the point of totally gloomy - I really don't think I would use it again.

How about inviting a mobile service to your home to get you started in deciding what you like - alternately take some samples home from a store. There are good online blind companies that will save a lot and will send you samples. You can also ask your local fabric stores which fabric lines they stock - You can then look online at your leisure and select some favourites. Go back inshore this will help the consultant know what you like.

Great find, they are awesome! At first glance I would've placed them as Mid Century Modern. They are very similar to chairs designed by Philippe Starck, in particular 'Pratfall' and 'King Costes' chairs.

Most curtains (except sheers) benefit from the weighted hem as mentioned previously. You could also try 'training' the fabric to stack and fall, by folding concertina style across the width of each curtain. The outward pleats should match your pinch pleats, with the gully between them. It's a little fiddly to get right, as fabrics are usually off-grain, but well worth the effort. Loosely tie them with tape, ribbon etc. close to both the header tape and the hem for a few hours, or overnight. If your curtains are long and/or heavy, another tie in the middle may be needed. They should continue to drape well once released. If your rail has a cord closing mechanism (not hand drawn), it should be possible to release some cord to help the front slider cross in front of the secondary slider. However, if the weight of fabric is pulling the rail down, the rail could need extra support across its length, or a sturdier model... Hope this helps!