1. You need to finish your journey at the point of origin, this is not on the OWE rule, but recognized as a common rule for published excursion fares. Confirmed with AA. Maybe, on a rare case by case basis, some people possibly receive exceptions for ending in different cities (never have done it nor heard of it so don't know for sure). However, between Canada and the US, a quite definite no. They are not considered the same country (fare basis differential is quite substantial).

2. You are required to end the trip in the city where you started. Your routing must include a final flight back to your point of origin, and must be ticketed accordingly. However, unlike missing your first segment, airlines usually don't pay much attention to missed last segments. In other words, even if you miss your last ORD-YVR flight, you probably won't be penalized.