I dont believe there is a list of specific costs as they are all variable depending on partner and destination. The award chart mentions the following:
General statement:
All awards are based on one round-trip ticket between North America and destinations noted. Please be sure to view our North America Definitions page, as each of our partners may define it differently.
The purchaser of an award ticket is responsible for all applicable taxes, fees, and checked baggage charges imposed by the transporting carrier(s) or U.S. or international authorities.
A $25 (USD) nonrefundable fee will be collected per person for each award booked on a partner airline.
When you see at BA award chart it says the following:
Fuel Surcharge: British Airways mandates a fuel surcharge fee, ranging from approximately $150 to over $1000 (USD), for all awards redeemed by Mileage Plan members.
Change fees would be the same as what they are for AS revenue tickets