Idea

In general, I would recommend that separate discussions be posted in distinct threads, to prevent confusion.

For friends in the Game Manager, there was actually one other post requesting this, here: https://community.playfab.com/hc/en-us/community/posts/206730137-Tab-for-friends-of-players. The recommendation here would be that users vote up the previous request, so that we can more easily see its aggregate votes.

For the Add/Remove friend calls in the API docs, the "Try It Now" functionality is designed for you to be able to validate the logic, and it uses a player entity with your title which, while consistent, is not going to be a specific player from your game. So if you use AddFriends and then GetFriendsList, you'll see that the player(s) you added are in the list (and so would then show up in a call to get a friend leaderboard).

For player online status,there are a couple of threads I would recommend reviewing.

https://community.playfab.com/hc/en-us/community/posts/206710727-Is-there-a-logout-request-in-the-API-?flash_digest=313a31f181d08a84e1b6bdd5f4b622575d1667d0

https://community.playfab.com/hc/en-us/community/posts/209020277-API-Logout-Call

Friends for the player are now in the Game Manager dashboard.