chuck and homer are stored inside the php file in an array, so yes, modifying those files will add additional items. The quotes module stores the quotes in the DB, so you would have to edit them there.

As far as making new modules similar to homer or chuck or beer or something similar, you can just copy the module to a new file, make sure you change all the commands to match the new file, and make sure that command doesn't conflict with any other command.

I did that recently with beer, making a wine module as one person in org doesn't drink beer. Best line in wine:

!wine = The california raisins after they retired