A:AnswerThere are apps that will alert samsung users of a near by unknown airtag. But it wont make a sound from the tag if that is what you are asking.
A:AnswerIt’s my understanding that it’s only limited to cell service or access to other apple devices. I easily tracked a bag across the Denver airport and was able to retrieve it in the lost baggage area in a matter of minutes.
A:AnswerYou can put an air tag in your car to find it, but it’s easier to use maps to locate exactly where you parked. The air tag beeps fairly quietly. You need to be close to hear it. The find arrow will point you in the direction of your car very accurately.
I’m not sure I understand your other question. You can say put it in your child’s back pack and track their back pack. If you share your location in family then anyone you share with will see their locations. My son and my share our location so any item I am signed into Apple with he can see and find using his iPhone, or iPad or MacBook.
A:AnswerIf you still have an old device with the same apple id you connected the airtag to, you can remove the airtag and connect it to another new apple id. Another option is to share the airtag with another apple id from the main device.