1) Only Guard Infantry (or other units specifically mentioned in the doctrine) can take doctrines. Reread your codex.
2) Only units with a voxcaster can use the voxcaster. If the support squads are within 12" of the Command Squad, then yes they can use the officers modified LD, otherwise, no.
Benconnor Independent Commando
Lesson for the Month: Hug cover until the Armour arrives. If you don't have Armour, take that objective and hold it.