From what I can read online, you're not the only one who's had problems with Debian + laptop + usb - someone even suggested that there was a bug in the install scripts. Their solution was to do only the "minimal" install, and then upgrade everything via apt-get once the system was working (here
, for reference' sake).
And if you get to a command prompt like that, after you login, the command to start X is "startx". If you can get to that prompt again, you might try that and see if it works