(ii) Two hebrew words are used...
(1) Shamar (8104) - a primitive root; properly, to hedge about (as with thorns), i.e. guard; generally, to protect, attend to, etc.:
(2) Natar (5201) - a primitive root; to guard; figuratively, to cherish (anger):
(iii) Church leaders or those in positions of authority to watch over others.
(iv) (1) (a) 5:7
(b) 1 Pet 5:2
(2) (a) 8:11
(b) as above