You must call in for stopovers, multi-city, or complicated routings, until the new booking system launches in 2021.

I hope others will significantly improve this wiki!

There are four zones: North America (inc Central), South America, Atlantic (including India and Western Russia), Pacific (inc Eastern Russia) and the chart is based which one you start from and which one you end up in, there's ten of these.

Cost is based on distance, which zone pair your flight is in, which class you are flying in.

Partner airlines (again) are a better deal because while Air Canada will calculate cost on a wide ranges but partner airlines are fixed to the bottom of the range.

YQ is eliminated. There's a 39 CAD fee for booking a ticket which contains a flight on a partner airline. Aside from this, there's no incentive any more to book a return flight it seems and every incentive not to.
Note: The partner booking fee is refundable, so it's basically a YQ, rather than a booking fee.

Most flights are devalued. However, the elimination of YQ sweetens this significantly. Within North America, a lot of flights became cheaper, YVR-HNL very significantly. YVR-TYO is much cheaper while YVR-AKL is a little cheaper.

A vastly more powerful booking system is promised for 2021.

There are a lot of new tricks to be learned. https://princeoftravel.com/blog/new-aeroplan-flight-rewards/ is a good start.

Information that is harder to find:

• SE IKK redemption from the old program can be changed ("within reason") without repricing. Dates, routings, no problem. Origin/destination should be fine. But nothing that would have required a repricing under the old program. This is from Mark Nasr in https://www.facebook.com/pointsmiles...44878252851420
• The "Activity" page only shows you the most recent ~48 transactions. See this post for information on how to get older data.
• A partial refund may not be possible (e.g. if you book RT and outbound flight is cancelled by you or AC, to delete the first flight segment, you have to cancel the entire ticket and rebook the inbound at a potentially higher fare. It seems supervisor can grant exceptions.)