In regards to Hannibal knowing, I am reminded of an episode in the first season where Hannibal was talking about how it's rarely the actual meat that you eat that gives it it's value, and more about how it's presented to you, hence why extremely expensive beef doesn't really taste different, but just the fact that you paid that price for it makes it seem different to you. So, presenting this idea to Hannibal in that way as kind of huge boon would make him less critical of what's in his mouth? I mean, I don't know, there generally speaking isn't a huge difference in taste between red meats (at least, to me).
I kind of still doubt Will actually went cannibal, but we'll see by season's end, I'm sure.