As regards the good Ludwig, I was listening to Classical FM this morning and they actually answered that one - they have a kind of musical almanach out at the moment to plug. It seems he himself acknowledged it was a term he added to his name, one presumes to be able to adopt a sense of august authority, to hold his head up with the Baron von Munchausens around him. 'van' is in any case at best Low German, and he was not from an area where Low German was spoken, born and bred in Bonn before settling in Vienna where he lived out his life: I suppose he chose the Low form to protect himself from any accusation of aping his betters, which would have been dangerous to his career at that time.