There are other methods of identification besides tags. Chipping comes to mind as well as tattooing. Tattooing would be a bit extreme but it does happen. Chipping the dog is not a bad option.
Whether you keep your dog collared or not, I think it depends on the situation of how the dog is being handled and where they are kept, kennel, outdoors loose or kenneled outdoors etc. I don't think there is a silver bullet answer. Inside kennel absolutely no collars in the kennel period. Outside they should be ok. Maybe a break away collar in an outside kennel if they even make those for dogs. All it takes is a dog getting a collar snagged and it's not going to end well, been there seen that on a personal experience. Be careful with collars and kennels.
As far as walking, I don't think a harness is necessary if the dog has been trained properly to either heel or loose leash walk beside you. A collar will work just fine.
Sent from Petguide.com Free App