For scaly water spots I always start with a product called "One Grand Special Touch". Specifically formulated for water spots. I've not seen many spots that it would not remove. (I've had my bottle for so long I can't even remember where I bought it... internet search should yield results.)
For very severe water spotting, you will need to polish. I use a PC with LC Orange pad and either M105 or M205 depending on how bad the water spots are.
I would recommend Blackfire Wet Diamond (2 coats) for protection. But no product will actually repel water spots. The goal would be to have her park away from the sprinklers!!! (Haha!) :biggrin::biggrin::biggrin::biggrin: