Must I make up the days I broke my fast in Ramadan when I was young, along with expiation, or is it sufficient to just make them up and feed one needy person?

What we rule on our website is that there is no expiation (kaffarah) upon you, because expiation is only obligatory for breaking the fast by intercourse, and this is the view of the majority of scholars. You are at liberty to act upon this opinion, and you are not obliged to act upon the view of the Malikis. Accordingly, what is obligatory upon you is only to make up for those days, and you must feed one poor person for each day you delayed making it up until the next Ramadan came, which is the view of the majority of scholars that we rule by.