Which is better for someone who missed Maghrib prayer with the congregation: should he be led by someone who prayed Maghrib in congregation, or should he lead someone who prayed Maghrib in congregation? And in the second case, must the follower repeat the prayer, or should he wait for the Imam?

The first [option] is that the one who missed the congregational prayer should lead as an Imam if he is qualified for it, because some scholars do not deem valid the prayer of one performing an obligatory prayer behind one performing a supererogatory prayer. The person who prayed in congregation, his second prayer is considered supererogatory (nafl) and a charity (sadaqa). It has not been reported that the follower should give the salutation after two rak'ahs if led by someone who missed the prayer.