What's the latest policy for UA? Will the gate give a jumpseater a boarding pass for business class? If the flight loads show Y as oversold, but plenty of open seats in J and F, should I not consider this flight as an option?

What are people's favorite airlines for jumpseating to Europe (with at least a chance of an upgrade)? I'm trying to get to Germany, but I can't find schedules for Kalitta, Atlas or any other ACMI besides Polar. Should I just call their jumpseat phone numbers?