Did Allah use angels as a medium of communication for all the Prophets and Messengers?
I have read that Allah spoke to Musa (AS). Was he also sent an angel (malak) later?
Yes, of course. There are two angels that aways stay with us. A angel visits us right before we die and some other types of angels visit us during our lifetime. Angels visit everyone and therefore they visited all prophets and messengers (peace be upon them all).
There is a specific angel whose job is to bring holy scripture to the messengers. He is jibraeel. He delivered the message of Allah to our beloved messengers. I don't know if it applies to prophets who didn't receive any scripture.