Chinatown in Vancouver is less of a tourist attraction, and more of a market type of neighborhood known for its proximity to low income housing and drug use. There are some great eateries and shops in the district. Maybe a few small gardens as well.

If you venture out to Richmond (the city in which the airport is situated), you will encounter virtually a whole Chinese/Hong Kong feel in which there are restaurants galore, billiard halls, gaming stores, and people driving flashy cars around town. Make sure to visit at night because Richmond is a ghost town in the early mornings, especially on weekends.

Cantonese is widely spoken, yes. You will not have a problem speaking it in the areas I just mentioned.