In tennis can you hit the ball at your opponent's instead of by them?
it would be easier for them not to return right?
If your opponent ducks and turns away, you are supposed to avoid hitting them. Otherwise it's acceptable in tournament play. Social situations will have their own rules...about which I am even less qualified to comment.
You could, but it would probably be frowned upon.
No the point is to have them running back and forth. They will return it if its hit at them