Well, these spray wax can be apply to glass, but with a very minimal use. I mean that you spray a bit, only mist then wipe till dry. Why? Because too much product can make your wiper hard to move, like leaving some residue in the windscreen when you get into rain(sort of smearing thing, like when you put thick coats and thin coats).
For window I really recommend using the Ultimate detailer, not Ultimate quick wax. You can use Ultimate quik wax but put it on the microfibre cloth. Then you wipe to the wind screen, because it contains waxes and all the stuff more than the UQD.
But to be honest, if you want water not touching your windscreen and all that stuff, try glass polish. It will make water beads damn well and not even leave any water marks. But as Kieran said, labour intensive and took long time to finish it. Glass polish that I recommend: Glass Science product(not available in OZ but should be able buy online), then Sonax glass polish from Germany(available at local car store).
Anyway Hamish, to answer about polishing, COLORX is only AIO product, which I mention before above to Chris. If you want pure polish and you're still doing with hand, try to use Ultimate compound.
Thanks