1) Yes, AC uses the (great!) NZ lounge at SYD, so there'll be a boarding call, and usually a visit from a concierge there.

2) Sorry, it's been a while since I've done SYD-YVR so I've forgotten the precise sequence of meals, but it'll be the "more elaborate new style catering".

3) Again, my experience of YVR international arrivals at that time of the day is limited, so I'll leave it to the locals to comment [my experience of YVR customs & immigration is either no lines, or horribly long lines, but rarely anything in between!].

4) The YVR arrivals lounge is OK - showers and snacks, perfectly adequate after a long flight. It's located landside (i.e. after customs & immigration). It's a bit hidden away - carry on out into the public arrivals area and it's on the right hand side (near Starbucks) down a short corridor. Since sometime earlier this year this lounge is no longer operated by AC, but is now called the Plaza Premium Arrivals Lounge (but of course Executive First and SE/E still get free access)

Have a great trip, mad_atta!