when I was doing the body work on my Duster, I was able to pull a few of them out with the glass in place, but not all of them. I imagine the same thing would be in effect when trying to put them in with the windshield in place (although if you could start the screws at an angle that works with the gasket, that would work).
Nope. Screws or studs are used to hold the clips on. You might be able to get away with it if it uses studs but taking the chance of breaking the glass is not worth it.