1. They are not independent and more than often (more like 99% of the time) are from the exact same pool. Not weird. You could get 2 on your preferred flight and 2 on another, given that there are 2-3 YVR flights every day. At least everyone is getting there in this case. For the 2 that settle with the less preferred flight, just set up a waitlist to switch to the better flight so they can confirm you when (and if) seats open later down the road.

2. 4th option after 'redeem flights' from the homepage, 'flight award re-booking'. But it can't be guaranteed to work given CX IT