"Could not look up Internet address for localuser. This will prevent GNOME from operating correctly. It may be possible to correct the problem by adding localuser to the file /etc/hosts."
to solve this just do as it says, add the line
to your /etc/hosts file. As for the different mac address error, I think you can solve this by adding alias information to the
following lines to your /etc/modprobe.conf file
alias ath0 ath_pci
however for a full round-up make sure you read