Hi guys,
thanks to all the info here I finally figured it all out. I installed the drivers and just ignored the looping error message (closed that terminal). I opened a new terminal and did modprobe ath9k. I also figured out what mon0 is (to help out other noobs: it is the new virtual interface created by airmon-ng when you run "airmon-ng start wlan0" to put your wireless card into monitor mode. You will use this for any other commands further on, such as the injection thingie in aireplay-ng or capturing in airodump-ng, instead of wlan0). You don't need to do anything to enable the card except the modprobe ath9k command. If anyone could tell me exactly how to make this command (modprobe ath9k) run automatically on startup, I would greatly appreciate it!