I am doing this from memory but if you go into the reservation in virtuallythere (click link in confirmation email) if you look closely at each flight segment it will give you the airline confirmation code or file#. Alternately you can find the ticket number and use that as well on AC's site.

They will allow you to request a higher fare code in economy. I booked 2 tickets to New Zealand in Premium Economy and they gave me the full $2,000 per ticket.

I also just booked on the website, worked well, but it may not let you choose higher fare code.

Incidentally, if you also have an RBC US$ Visa they will allow you to transfer the Reward Points into your Avion account 1 for 1, but you have to do it over the phone.