I highly doubt that the virus will corrupt your Wii. If the virus corrupts your files, I think the Wii simply won't be able to read the files.
I can't answer your question about the virus affecting your files because there are different viruses that do different things.
Well, the virus makes an autorun.inf appear on my SD card.
My antivirus deletes it, but it eventually reappears like 2 or 3 seconds later.