You'll have to check in at a 6E counter. You will not receive lounge access in DOH, despite the QR flight number. You will receive Avios, as long as you are crediting to QR (not BA or IB). And you will be eligible for a free meal onboard. Show your boarding pass to the crew when they roll the snack trolley down the aisle (your boarding pass will show "QRCS" and "QRML" which indicate to the crew that you are travelling on a QR codeshare flight and eligible for a free meal).

To be honest, given the relatively short distance from DOH to India, I don't mind 6E-operated flights, especially because the timings are so much more convenient (and usually cheaper than QR-operated flights). 6E crews are generally friendly and extremely efficient. Just make sure you bring your own entertainment and a power bank.