You may investigate the possibility to use wicd (wireless interface connection daemon), which is wonderful if it functions with your dist/version/wificard. Conflicts with wlanmanager though so may be tedious to test if you cannot verify functionality on beforehand.
On the other hand, there may be a possibility to use ifconfig/ifup/ifdown after boot with network not always fully configured (happens to me just now sometimes, don't know why, after upgrade to ubuntu jaunty). The procedure I use is:
sudo ifconfig [tells that my interface IS configured but lacks IPno]
sudo ifdown ath0 [brings my Atheros card down in order to make next possible]
sudo ifup ath0 [brings it up and aquires an IPno from my router; did not succeed at boot, why?]
Hopefully, the WLAN should function now, and you may see an IPno with another ifconfig if all is in order.
Now my card is Atheros (ath0), use your actual device instead. Note: The ifup procedure may perform additional exercises regarding mounts and some other daemons as well but don't worry.
For me this is a temporal solution until I get my wicd running again (I am in a quadruple transition as regards major upgrades of Wicd, Ubuntu, KDE, and the Atheros driver for the Linux kernel, so it may take some time).
Hope you will come to a solution!
P.S. I don't dare trying answer your questions -- very similar to my own ...
Last edited by toreric; 08-03-2009 at 12:55 PM.