To preen just means to groom the feathers. Birds may do this to their young and possibly other birds. If they like you, they might try to do this to your hair.
Grooming themselves.
Similar in size, if you mean common pigeon as the rock dove.
It means they are in the same flock
Yes
it means that a pigeon died outside of a church...
Pigeon-livered/lacking gall = timid, easily frightened
would it be to do with the pigeon being a bird and bird meaning a pretty girl
It means that they are in love with you.
It means nothing other than the pigeon just happened to show up.
No, a pigeon is a bird of song that lives in urban areas. because they live in urban areas much of their diet is human food.
Means that it is dead.
What does it mean when tow gray doves land on your deck