I used to replace the gpu coolers (with termaltake and accelero coolers) but with non reference designs getting better and better i dont think is really needed anymore.

To do that you need to:

1-Backup your files, then use the Windows 7 dvd to format and install the new OS.

2-Install the remaining drivers (gpu, audio, etc.). You can find those easily online.

3-???????

4-Profit

If i remember correctly, you just need to unplugg the gamecube controller. After that the console should pick your controller just fine (if it doesnt try sync them again).

Sure, why not?

Im using a Internal Hard Drive (750gb) from my old PC with an External Enclosure (this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16817182155). Everything is working perfect so far andit was super cheap (20$). Internal Hard Drives are super cheap, you can get a 500gb for 50 to 60 bucks.