Baggage transfer from international to domestic and vice versa at Kunming Airpport

I am likely to fly next week from YVR to CCU . First stop over at Shanghai then to KM which requires transfer to domestic terminal and then from KM to Kolkata another transfer from domestic to international terminal. Can I through my checked in luggage directly from Vancouver to Kolkata? Or, every time I have to collect my checked in baggage and have to go through the customs ?
Also, can I use my credit card to purchase food and any other cost at the airport?