Propaganda doesn't totally rob people of agency free will (more accurate term), if it did this site wouldn't exist. People do have the capacity to develop critical thinking, skepticism, and a basic curiosity about the world that allow them to develop some resistance to propaganda.
You can hold people accountable for failing to even attempt to do this.
No, but this doesn't really map properly into the real world. People don't just receive discrete, neutral information which they either do or don't have the training to verify. The circumstances that lead to the development of ideology (bourgeois or proleratian) vary wildly and some people get radicalized into good comrades by mostly the same conditions that turn others into Klansmen. We do have a right to get a little bit angry at people who fall for propaganda.
Again, I very much recommend reading up on Classical Conditioning.
me, a beast: waking up
my scientist: let's put that beast in a situation
me: yes honey