Bamboo roller blinds are an inexpensive fix. They can be cut to fit and have a decorative look.

First you need to decide on the look you want to have on your bathroom. If it is classical stained glass suits the better and for modern go for frosted glass. But before going to stained glass make sure that the bathroom furnishing and fittings should be in a classical type. Where as for the frosted the bathroom furnishing and fittings are readily available in the market.

You don't necessarily need only paintings as artwork. You can put some floating shelves near the dining space with some good crockery like plates or tea sets which can be used for occasions as well. On the wall in the living space you could keep either traditional or modern show pieces.

Keeping non fixed windows in basement is not of much use as from inside they are above our head level and we barely have to use them to open them