For your window question there is a way you can do it. I would say add a new switch, one push or slide or whatever and all four windows will roll down automatically. Or have the switch be a master, so when it was activated you can just hit the passenger side window and control all four windows, including auto down. haha.
You can actually do anything you want with the windows, just a matter of finding a wiring diagram or what wire is what and figuring out how to make it work, using relays and such.
As for the floor mats I've seen G6 specific ones online for under $100. ebay is pretty good too. or you can check a dealer. or really almost any store that sells automotive stuff, walmart. autozone, pepboys, i've seen floor mats at all of those places