I would not suggest fabric window treatments in the shower. I would consider an opaque window instead.

Depends on your budget. Can you describe the situation and add more photos. There are several threads on this topic in Design Dilemma already. To sum up, the options are- replace window, replace wood trim with vinyl, cover window with something completely water tight, or hang a plastic curtain over the existing window. Switching to a different shower head with a narrower flow of water may reduce the amount of water that hits the window.

Agree with APO - and if you are looking to make the room appear larger consider adding clear glass shower doors. Good luck.

Windows in showers equate to moisture damage. It's a matter of when not if. It's poor design. The design needs to be changed, or you need to plan on funding a savings account to deal with the rot and mold.