The activated ability of the token doesn't target any card in your graveyard. You choose the card named Deathpact Angel, if any, when the ability resolves.

The activated ability is part of the Cleric token's copiable values. Any copy of that creature token will also have that ability.

The card named Deathpact Angel that you return to the battlefield doesn't necessarily have to be the same one that created the token you sacrificed.