sql join query for complete and partial data

Sorry for my English. I have two tables: users and friends. I can not use amounted join query to retrieve data about users. The first request - show users if they are at each other's friends list.

id|id_friend
 1|2
 2|1
 3|1
 1|3
 1|6
 7|1

If I have id = 1, then get friend with id = 2 and 3.

The second request - to show people who have sent a request, but did not receive a response. If I have id = 1, then get only friend with id = 6.

The third request - show people who do not approve the request. If I have id = 1, then get only friend with id = 7.

If I use this query, you get 2, 3, 6:

SELECT * FROM users INNER JOIN friends ON friends.id = 1 AND users.id = friends.id_friend