Ok for a start you should not feed wild birds.
But many people do.
So my thoughts are
-You should not feed them very much as they are very capable of looking after themselves and will not starve if you go away for a few days.
– You should be very careful not to catch or pass on any diseases.
– Be very careful what you feed them. A lot of advice on the net about this. They are INSECTIVORES but seem to eat anything they find. I saw Missy darting under a hedge the other day with the remains of a small quiche she had liberated from the school grounds. I feed my lot with a small amount of mince mixed with insectivore supplement. I have heard of people feeding them bread including jam sandwiches,cheese or pet food. DO NOT OVERFEED.
I don’t think there is much danger of changing their behaviour as we have created the perfect environment for them by mowing lawns, nature strips and sporting grounds. Look around, most birds can be found around human habitation. Look at the distance between territories on a country road. Often kilometres. They are ground dwelling birds who only use trees for safety and nesting. Bush and long grass would be dangerous. They walk like us and do not hop like some other birds so a nice cut lawn is perfect.