! Some of the answers you are looking for are dependent upon the Flight numbers DOH-HKG and HKG-DOH. If they are QR flight numbers (QR5801 and QR5800) then QR is the 'Marketing Carrier' whereas for CX640 and CX645 CX is the Marketing Carrier. CX is the operating Carrie for both flights. With your itinerary then CX is also the
Most Significant Carrier'. These are IATA terms used for various purposes such calculation baggage allowance. If QR is the Mstketing Carrier then you baggage allowance is 40kgs. but only 30kgs if CX is the Marleting Carrier.
1. Has anything changed with regards to the OLCI situation?
The only change is that check-in staff may now cancel both OLCIs. However knowing QRs almost total lack of communication not all check-in staff may know it even yet.
2. Do you check-in at the CX desks at HKG?
You check-in at the desks of the first operating carrier. Thus you use QR in ARN and CX in HKG.
3. Can bags be checked through from HKG-DOH-ARN-LHR, where the final leg is a separate BA award booking?
Yes since QR, CX and BA have baggage interlining agreements with each other within OW. But you should check-in for rhe ARN-LHR flight at the same time as the other flights in HKG.
4. Are people still experiencing problems with crediting these flights? I will be crediting to BA, but if this fails, I could also credit to CX or QF (not QR)
There stil appears to be problems with qr systems capturing codehare flights so a retro claim may be required. As others have experienced you MUST have your BAEC number on your booking. How long crediting your BA account takes I do not know, maybe others with experience of can tell you.