Good practice if you switch BIOS is to reformat the comp, but in this case i dont think you have a choice. Reformat the HD with whatever it had on it, changing the bios probably caused driver/hardware conflicts and is causing the system to BSOD.
Yep, entirely possible. Just go to where you have the music files stored, copy them over to the flashdrive and just plug it right into the laptop. I do it all the time.
The chances of you getting a virus from a flashdrive are less likely than you getting struck by lightning. But, if you really must have your mind at rest, you can disable usb ports in the bios of your computer at boot.
Probably means that the resolution your trying to play it in isnt supported by the game, try switching to 1280x1024 and running it to see what happens.