Hey, I was curious of what you think of the English voices?
They're really, really well-done. Much better than the JP voices by far.
How careful should you be with the food in general? Can you end up being really "wasteful"? Do creatures have like, one magical special item they should be fed that you have to randomly figure out or something like that?
In the early game, food is very easy to come by, so there's no worry about wasting food except for the rare stuff later on. That said, as I mentioned above, your familiars have a growth limit so they can only raise stats a certain number of times per heart rank. So if you're the min/maxing type, you'd want to only feed the stuff that raises the stats you're interested in. However, I should point out that later on, this becomes pretty troublesome, because especially in the third evolutions for familiars, it starts taking a crapton of treats to get a stat to raise. For evolving your familiars, you use special items whose only purpose is to evolve, so you also don't really have to worry much about that.