I'm surprised no one mentioned Boot Camp. Free (comes with MacOS) . All you need is a copy of Windows, and you can dual-boot your Mac with Windows. Benefit over virtualisation is that you get 100% of your hardware performance, especially when it comes to graphic.
Did you get your keyboard sorted? I cleaned mine yesterday, and got very similar results ( q1w2e3r4t5y6 ). Now the macbook won't even turn on if the keyboard is plugged in to the mother board :(
I'm running 6 GB with no issues whatsoever. Had installed 8 GB for about a day, didn't have any problems, unfortunately had to give one module back to it's owner :(
