Setting 'n' or 'a' Mode, and WPA2?

[Delphi Real Estate <Info@delphi-real-estate.com>]

I want to switch to 802.11a for streaming media, so I'm not polluting everyone else's bandwidth.  Does anyone know how I set the 4965 to 'a' or 'n' only?  Is there any way to set it to dual-band for the new routers which send normal traffic on 'g' and stream on 'a'?  How do I set it to WPA2 only?  

IOW, how do I control this card?  Instructions are nowhere to be found.

Currently my /etc/network/interfaces file is set thus and works (Network Manager is uninstalled and I don't trust it):
iface wlan0 inet static
pre-up /sbin/iwconfig wlan0 txpower 5
pre-up ip link set wlan0 up
address 192.168.1.1
netmask 255.255.255.0
gateway 192.168.1.5
wireless-essid Hex
wpa-scan-ssid 0
wpa-ap-scan 1
wpa-ssid Hex
wpa-psk Freeasinfreedom