Try wide mouthed jam-jelly jars. They are easier to clean, will stack nicely and are about the size and shape of a tumbler. Ball Mason makes some nice ones.

Does anyone know what that branch/ lighting piece hanging from the ceiling in the first picture is? And where to get it?

I second the thought of sliding Japanese paper screens (shoji) or even one solid built in one. It would soften the space and you can get the paper in plain white or with watermarked patterns (from ...

If you don't want to do it yourself, try Etsy.com. You can contact a local artisan screenprinter through the shop local function (near the bottom of the page) or you can take bids for the job from ...