As long as your hubby was in OPT status, you were in legal F2 status and no need to extend your F2. Your hubby's I-20 with OPT note will prove that you are under his I-20 with OPT status.
-Not automatically. You need to tell the International Student Office to extend the F2 status for you when your spouse extended his F1 (e.g. application for OPT). Then, the International Student Office will put the F2 extension information into SEVIS (not need USCIS approval). Otherwise, the F2 statud does not count to be extended.
