Hope this is not too late. I do similar flights all the time YVR-YYC-AMS

1. If you booked the journey as one ticket with KL, you will get your KL allowance. In Y 1x checked & 1x carry-on.

2. Encores Dash-8s have ample room in the overhead bins for standard sized carry-ons. I only travel with carry-on and often get Encore segments from YVR-YYC.

3. Yes, you check in at Westjet (WS) counter. Always double check your seat assignments with the WS agent, especially if you are in J. WS agents are obviously not very knowledgable about AF/KL seat/fare classes. If I book J WS agent often puts me in WS Y seats when you are entitled to WS Plus seat.

4. I travel YVR-YYC-AMS a couple times a year. WS has a lot of connecting pax for AF/KL. WS is now a FB partner airline. You can earn and burn FB award miles on WS, but not status level miles. Maybe in the future WS will be a full Skyteam member?