There are no age restrictions on ownership. However you do need to be of a certain age to have a contracted service. The age will vary depending on the local legislation.
no age at all as long as you get it
Put the iphone in a box of an old nokia phone and wait for them to open it up.
Sure. Most of them that is. Just check on the app's page on the App Store that it is compatible with the iOS version that your old iPhone is running.
3G is the service for things like the internet... just like in the old iphone there is Edge.
No. It was just an old rumor.
Not in my opinion
Yes
nvvjv
yes
Depends on how old they are
I'm assuming this is old as the iPhone has been out awhile, but no there is no return policy with Apple or AT&T.
Apple never released an iPhone 9. After the iPhone 8 and 8 Plus, the company skipped directly to the iPhone X (pronounced "ten") in 2017 to mark the 10th anniversary of the iPhone. Therefore, there is no age for an iPhone 9, as it does not exist in Apple's product lineup.