The definition for it is here:
https://altitude.aircanada.com/status/flight-passes
Flight Pass and Altitude members
Flight Passes make frequent travel with Air Canada even easier – and that should be rewarded.
All Altitude members have the ability to earn either eUpgrade Credits or Altitude Qualifying Miles for eligible Flight Pass activities beginning January 1 (or the day Altitude status is confirmed by e-mail) and December 31. Eligible Flight Pass activities are defined as:
The purchase of an eligible Flight Pass of 6, 8, 10, 16 or 20 flight credits in your name (excludes Unlimited Flight Passes and Flight Passes for Business).
The usage of every 10 eligible flight credits in conjunction with a Flight Pass for Business.
The duration of the travel period when you purchase an eligible Unlimited Flight Pass, on a monthly basis.
Note that promotional or time-limited Flight Passes may not be eligible.
In the past some flight passed have been excluded from that (such as the amazing sale of the World Pass in December 2013, which only had 4 credits), but a 6-pack Euro pass shouldn't have any issues with it.
Also, by their nature the flight passes book into a fixed fare class (such as M for the US Commuter pass), AFAIK. So the agent mentioned "even if you purchase a tango fare", I'm wondering if they were a bit confused. I'm also not sure if the concierge would be the best person to ask about this, compared to the AC Reservations number.
For the bonus AQM, you'll receive the 2500 miles a few days after purchasing the pass. Even if it's valid into the next year, you'll just receive that bonus once when you purchase a pass.