Do I have to “wipe” free space and/or files on a TrueCrypt volume?
Remark: to “wipe” = to securely erase; to overwrite sensitive data in order to render them unrecoverable. If you believe that an adversary will be able to decrypt the volume (for example that he will make you reveal the password), then the answer is yes. Otherwise, it is not necessary, because the volume is entirely encrypted.