I am confused about את again. Here I understand why it's needed: the pizza is getting something done to it - it's being eaten. In a previous sentence however ("You don't like chocolate?"), there was no את. Why? The chocolate was being liked (or not liked, as the case might be). Is it because in that sentence it was "a" chocolate and not "the" chocolate, which is why we don't use את when talking about it? I promise, some day I'll get it! :-) Thanks in advance!
You are correct :) את is used before the direct object in Hebrew, but only when we use the definite article ה (the). In Hebrew we call such nouns שמות עצם מיודעים. So for example -
אכלתי פיצה אתמול
אכלתי את הפיצה שקניתי בתל אביב