We also went out to see Terminal D on Saturday and were impressed. The airport did a pretty good job publicizing the open house...I hope the place is never that crowded again! Nice spread of continental breakfast and lots of giveaways from the vendors and airlines.
As noted, AC will not have a FL, but it appears to be a pretty nice AC. BA reps said that they will not have a Terraces/FIRST lounge but rather a shared airport-run lounge.
From the terminal maps, it appears as though the "major" international carriers (BA, LH, KL) will have dedicated gates, while the south half of Terminal D (gates 6-12) will be shared use (including Air Canada).
I agree 100% with the OP's comments on the garage...it is currently a nightmare and a traffic jam waiting to happen. Poor signage, idiotic traffic flows, too many tight turns and bottlenecks. I predict a major revamp before the terminal is one year old.
Another fearless prediction...most of the fancy sit-down restauarants will pull out before the terminal is a year old as well. Nice concept, but there aren't going to be enough departing flights from Terminal D to support that many sit-down restaurants inside the security area. Friday's will survive, and perhaps one other, as well as the more typical fast-food places.