1) Take the 5 or 6, and you’ll see that most passengers get on/off at Robson, Denman, Davie Village and/or English Bay (likely including some Cardero residents); between Denman and Jervis, you can often count the disembarking passengers on one hand, despite all the existing density. Gotta have destinations too - not just residences. Just look at Edmonds.
It’s also a little too optimistic to think the West End won’t get City Hall to bore Cardero anyway; it goes under a bikeway, after all.
2) West Van in general, sure, but Park Royal/Ambleside (the one pro-transit part of the district) and Horseshoe Bay are used by the whole metro. And I know firsthand that Kitsilano’s already pretty well-served by transit; the only real flaws are a lack of frequency and not having a bus down South Burrard. As for the Canada Line, it’s only at 6-7k pphpd out of 15k, and it’s supplemented by the Granville busway, so a relief line’s way down the list.
3) Dunno, by the time the Expo needs 75-90s, it likely
really needs 75-90s. I’d be the first one to say Waterfront’s not critical to the downtown network, but between local usage and people trying to get between the CBD and Lonsdale (and will still do that because Gold/Purple doesn’t save any time), it’s still busier than the entire Richmond segment or Coquitlam segment put together.
4) Perhaps your best bet is to have Gold built, then later branch it off into its own line with sub-branches to Park Royal and Arbutus. It’d need its own depot somewhere along Hastings, but otherwise you’ve got fairly good coverage without going overboard.