# who lead my people astray

"who lead my people to disobey me". Micah continues to speak judgment against false prophets.

# if one gives them something to eat, they proclaim, 'Peace.'

"they tell people who pay them even a small amount that things will go well for those people". Micah refers to a situation that actually happens. The phrase "something to eat" is an ironic way of speaking of a small payment. 

# if he puts nothing in their mouths, they dedicate themselves to wage war on him

"they do all they can to destroy people who pay them too little". The phrase "puts nothing in their mouths" is an ironic exaggeration for not giving what they want.