A clay bar should work on the paint and then keep a good coat of wax on it. Try not to let the water dry before getting it off. To make this a little easier, after washing get the car into the shade. If you can, wash the car in the shade also and rinse frequently. We have hard water here in the Las Vegas area and water spots are always a consideration. As for water spots on the glass, try using white vinegar to remove them. Put some in an old "Windex" bottle and spray it on just as you would a regular glass cleaner. You will problably have to do the glass a few times if the spots are baked on. The vinegar works on glass shower doors as well.