Kitchens and bathrooms add value universally. Bay windows may or may not add value. So unless its in the kitchen you might break even on value

Window leaks in general are from bad install most of the time. Usually from the flashing at the top.

Bay windows and skylights leak because of the window seals facing water. Its not sealed like an aquarium and pointing glass at water is fine but add uv rays/heat to the equation and seals break down even when properly flashed in