Broody means has she been collecting eggs and is she sitting on a nest? Is she laying?
Molt is when they lose a large amount of feathers over a period of time and grow in new ones usually once a year for big molt they also have mini molts but I don't think they would lose just their chest feathers.
Lice and mites are bugs that get on poultry and live off the bird. Mites are very tiny smaller than a speck of pepper and lice attach themselves to the feather shafts you can usually look around the vent area and see them they are light tannish, mites are black and they will hang around the vent area too and under wings. There are red mites too but I have never seen them.
Welcome to BYC hey I learn something new everyday about my crew and I have had them a good while