You can use natural stone like marble for floor but do not use granite for floor at all as it is very slippery when wet. As for tiles do not go for glazed vitrified tiles for the floor for the same reason. ( floor becomes slippery once wet and may cause mishap) Go for ceramic anti skid tiles that are specially meant for bathroom floor. For wall tiles you can use whatever you like and then decide over the matching anti skid floor tile/ marble. Double charged vitrified tiles are usually used for flooring in rest of the house.

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.

where is the reference image???

Consider swapping the door to the 4.5' wall for better flow. Arrange fixtures like toilet and vanity along the longer 5.5' wall. Place the tub/shower combo on the 4' side with the window. This opens up space and makes it easier to move around. Happy remodeling!