If I were to attach a wireless hard drive to the time capsule's USB, would I be able to back up to the external wirelessly? If not, how effect would storing personal data (not backups) on the external [through wireless, and then USB--> would that take much more time than just storing to the time capsule?]

What I am trying to do is attempt to store all of my files for school, movies, music, etc etc onto the external and use my time capsule for backups only. The time machine backup program will keep backing up until the space on the disk is filled (which is why I want to have data on a 2nd external). I have read a lot about partitioning the time capsule, and it seems as if it is not possible unless you do various operations (which I won't even think of trying). Any help would be greatly appreciated!