Does one fulfill the mitzvah of eating matza by eating machine-made shmurah matza? I saw that this was the minhag of the great Gaon Rabbi Isser Zalmen Meltzer. Does the box need to say anything special, or is it enough that it just says “shmurah machine-made matzah for Passover”?
Also, may one eat bananas for karpas, as was the minhag of Rabbi Teitz?
Yes, one would fulfill his obligation, nothing beyond what you write is necessary. Widespread custom is to use hand matza for the seder, if this is one’s custom they should abide by it.
Bananas should not be used for karpas, as one of the reasons given is that it is abnormal to eat vegetables before the meal and so it raises interest. Fruit before the meal is more common and would not accomplish this.