In the Mormon Church, only stake presidents may set apart Elders Quorum presidents.
The keys to the ministering of angels are evident when a holder of the Aaronic Priesthood receives Divine help in answer to prayer. Also, those who are righteous, with their sins forgiven through their baptism by the Aaronic Priesthood, would qualify for the ministering of angels.
The offices and duties of the Aaronic Priesthood are perfectly suited to young teen-age boys.
The priesthood has only been restricted from the descendants of Cain, which restriction was removed in a revelation in 1978, extending it to every worthy male.
In the Mormon Church, baptism and the sacrament are administered through the Aaronic Priesthood. The ministering of angels is connected to these ordinances.
The priesthood in the Mormon Church is not designed to rule. Mormon women, still equal, do not hold the priesthood because their duties are elsewhere.
We should trace our priesthood authority lineage through the records of the church from the highest ordination we have received.
A written record of priesthood line of authority is not necessary to exercise the priesthood, but it is a valuable thing to have.