If you had an account around when DD first came out, you would have had to create a new account anyway, since the forum server and software was changed in March of 03 (accounts were not transferred over to the new forum). Otherwise, you could have tried the password reminder function on the login page with any email addresses you may have used to register the first time to get you account info.
As for game controls, there is going to be an Xbox360 and PS3 port of the game, so it will be need to be controllable with a gamepad. In the unlikely event they scrap mouse support in the PC version for some reason, you still wouldn't be forced to use the keyboard as the primary controller.
The Larians have not said anything about game controls. The various mentions of WASD, etc were mostly in discussions about combat systems, which the Larians have also not revealed very much about.
