You don't need to allow for entry into the U.S. so you can treat any connections from Canada as a domestic flight. The only exceptions that I am aware of would be the CX flight to JFK or the PR one to LAS which do not preclear.

Preclearance in YVR (check in to gate) can take anywhere from just 5 minutes or less to well over an hour or even longer! It all depends on time of day, day of week and season. I'd give it at least 1 1/2 -2 hours.