No... OEM does NOT mean made by the producer of the finished product. It only means the company that produced the equipment originally installed in the finished product. So for Wilson, OEM drivers would be SEAS, ScanSpeak, and Focal.
Uhh, yeah it mostly does. On a Ford, OEM means a fender or bumper cover or other genuine part made by them (though the part may be made for them by a subcontractor). Completely third party parts like tires are not OEM. SEAS, ScanSpeak, and Focal are not subcontractors, they are the equivalent of Firestone, Goodyear, and Michelin. Off the shelf, stock, or third-party.