.tar is an archive. I'm using WinRAR, but I'm sure you can Google for plenty of other apps to untar files.
As far as the lower-right, if you read the FAQ, you would deduce that one is for the wireless and the other is for a USBGecko.
I'll go ahead and not answer all these other questions so as not to encourage such questions.
i.e. - Linux question. WiiBrew and Google.