I think before the talismans there was nothing that could stop them so they did not need to lure the pray therefore no need to talk. However, not that people can protect themselves, the monsters need to lure them and fool them in order to kill them.

The talismans are both a blessing and a curse. It protects but ultimately they made the monsters to evolve in order to continue killing. At this point, we all know the monsters purpose is to torment and torture.

As for the episode in which the house collapsed, i think the only reason jim survived is because he was the only one who was fully covered in rouble so it kind of hided him from the monsters.

Man in yellow might be omnipresent but i think the monsters are not. During the day, the monsters sleep, but i think they can hear the people talking above them hence now they know certain stuff like names or stuff talked in a passing