Does apple associate apple ids with the device? I made 2 different accounts with my ipad, one for my son and one for my daughter. Does apple somehow associate those accounts with some sort of serial number unique to each device (my ipad in this case)?
Apple will not link the Apple ID with the device unless you use the ID. Turning on services such as Find My iPhone will result in linking the device and the Apple ID so you can find it. This means that if you lose it, go to icloud.com, and report it as lost, the device will lock itself and ONLY the password of the linked ID can unlock the device (also known as "bricking up"). I'm not sure if you can use an account for App Store and a different one for iCloud.