On your paint problem I can't be much help. This usually happens because of damp -- please get a damp expert to make sure that there isn't any damp lurking in your walls. I had this once when I had pipes leaking inside the walls. I didn't know that. The other alternative is something like painting before the plaster is dry or some kind of chemical mismatch. I do know you will have to scrape all the mucky powdery stuff away and start again, at least on those areas. Don't try to seal and prime and repaint until you know exactly what the problem is and how to fix it.

I think you should stay with a simple pattern for draperies. Possibly a pattern incorporating the white trim and warm yellow walls. This would be soft and understated and something that you wouldn't get tired of easily. Other colors could be introduced with accessories.

Looks like some of them open...it would be cool to get some glass paint and paint the windows to look like stained glass...just pick you favorite colors and go at it

You will need to talk to an architect or perhaps a glazing vendor who specializes in curtain systems. They will likely provide the shop drawings necessary. Curtain systems are not something I'd attempt without help if you aren't an architect. There are too many variables, too many different ways to go, lots of options (storefront, spider, etc).