Sentence 1: The word "subsitency" is archaic and won't appear in many dictionaries. Virtually all native English speakers will assume you made a mistake and meant "subsistence." It would also be better form to say "Their father," rather than "the father."
Sentence 2: A native speaker would probably say: Lincoln worked many different jobs in his youth.
Sentence 3, would flow more smoothly if written as follows: Many college students work part-time jobs.