First of all, I am a modern Orthodox Jew; I keep kosher and always have.
Most Jews fast on the day of death, but it is optional; it is the usual custom in our community, but whatever the local rabbi says is what you should follow.
And, by the way, when a Jew says that they are fasting for three days, it doesn’t mean we aren’t eating anything for three days. That would be ridiculous. What it means is that every night, we break the fast and fast again the next day. I don’t agree with you about the amount of food that people bring though; it’s actually quite rare in my neck of the woods for people to bring food to a house of mourning (not counting the minor denominations of Conservatives and Reforms in the community; I know very little about them, since there are so few, compared to the 1,000+ Orthodox families in the community).