I know the proper way to thaw frozen milk is overnight in the fridge; but if I forget to do it the night before, can I just thaw the frozen milk in a bowl of hot water?

You can hold it under running water - start with cool water and slowly increase the temperature for quicker thawing. Once it has thawed, you can warm it up like usual. This Avent bottle warmer model is able to warm up frozen breast milk but it takes quite a while. http://kellymom.com/bf/pumpingmoms/milkstorage/milkstorage/