WPA2-AES , WPA2-PSK DHCP

I got my mini2440 board to work using WPA2-PSK with an USB dongle as
described in previous WLAN post.
I have DHCP script that works with the Ethernet connection.
1) How can I make my WPA2-PSK connection use DHCP instead of a static IP?
2) Is it possible to use WPA2-AES instead of WPA2-PSK?
   Does wpa_supplicant support it?

config:
network={
  ssid="DENGEBT"
  key_mgmt=WPA-PSK
  proto=WPA
  pairwise=CCMP TKIP
  group=CCMP TKIP
  psk="1234"
}
 
Startup:
ifconfig eth0 down
iwconfig wlan0 essid "DENGEBT" channel 4
ifconfig wlan0 192.168.1.111 up
route add default gw 192.168.1.2
echo "nameserver 10.0.0.2"> /etc/resolv.conf
wpa_supplicant -D wext -i wlan0 -c /etc/wpa-psk-tkip.conf &

Thanks
Any Help would be appreciated.

Hello David!

I would like to use wpa_supplicant too. can you be so kind to say me how
you add this package to kernel? 

regards

I did this:

$ wpa_supplicant -B -Dwext -iwlan0 -c/etc/wpa_supplicant.conf

It enables the access and the encryption to the wireless net

And then I run a simple

$ dhclient wlan0

That's all (at least here on my system).