Used to is used to describe past habits or long-lasting actions and situations which are now finished. People used to think the sun revolved around the earth. I used to take size 12, but now I take size 14.

* He used not to like reading. He didn't use to like reading. Both the above sentences are correct, but the second one is more common. *Used he to like reading? * Did he use to like reading? The second sentence is more common. The first one is old-fashioned.

The first two, and the last question are correct! Awesome work! Keep it up!