What are your favorite snacks in China?

This is going to sound weird because of a vocabulary issue, but ... sweet potato jerky. ("Jerky" is just the closest word I can use for what this stuff really is, but it doesn't cover how tender, sticky, and oh-so-sweet that it is.) "Spicy sticks" are also a guilty pleasure of mine. I grab a pack every second day or so and just eat them over the course of a day at work. And there's any number of street foods I love, with 锅盔 being my current favourite.

Are you fluent in both Mandarin and Cantonese?

Nope. Never touched Yue, Wu, Gan, Min, etc. at all. Mandarin is rough enough for me, thanks!