I thought I'd chime in here since I've flown DUS > LAS on EuroWings.

To answer your questions:

• Yes you will earn miles on the EW flight. It may take 2-3 days as per normal but will be per the accrual chart on UA
• Lounge access is complicated:
  • Does the airport have a LH Lounge? If yes, enter the lounge show your EW boarding pass and tell them you are a United frequent flyer (UA and NH FFs have carve outs that allow them to access LH lounges on any EW fare )
  • Otherwise - no
• Baggage will be per your fare and there are no *A benefits there

N.B. having been to the United Club at LAS you aren't missing out on anything!

That the flight is operated by a wet lease operator should have no bearing on the flight. You have a EW flight number and for all intents and purposes it is a EW flight.

Safe Travels,

James