How do I make a Leaderboard with Data Persistance?

I would like to be able to create a Leaderboard. I just want a normal leaderboard in the player list. (And data persistance.) Requested Items:

1. Code for Leaderboard
2. How to use above code for multiple score counts
3. How to make a button that gives the player some of the Score
4. Data persistance with auto saving every x minutes (x would be a variable i could change)