I just booked a round trip on QR IAD-DOH-IAD (in coach

). While booking the flight, I never saw a link to book seats, and when I finished it said something about confirming seats at check-in. Is there really no way to pre-assign seats on QR?
Also, what are my chances of getting exit row seats or bulkheads on this flight (I'm 6'-2" and like to work on my laptop while flying)? When flying EK to DOH earlier this month, my colleague and I were both lucky enough to get a whole row of 4 seats in the middle of the aircraft in both directions - what a luxury. I can only hope that these flights are this empty as well.
-Michael