I have no clue. Did you installed TDU before you tried to run TDU Platinum?
Is big bnk activated?
Try to check the compability mode of Platinum .exes, like the Paradise, TestDriveUnlimited, etc, and remove any compability they may have.
Online playing is being complex, due to errors with Project Paradise. So, i suggest you to install TDU, install Project Paradise individually, and create an online account. To have an online account, you need to mark check the gamespy box when creating the profile. Insert an email and a password, and the profile will be online.
If you get your online account up and running, install TDU Platinum.
It is possible. You need to edit the file located in Euro/Bnk/Sound/Radio
I believe so.