Accessing Android application data folder

I am building an application in which I want to use application specific data folder (the one with the application package name). I read a few documentation but they only confused me more.

There are a few question for which I need answers.

1. When is the application data folder created?
2. Where does this folder gets created? on internal storage of the device or on the sdCard or both?
3. What happens if we create the application data folder manually?
4. Does the app folder gets deleted if we uninstall the app?
5. What happens when we reinstall any app? will a fresh copy of app folder get generated.
6. Can we perform read/write operations on the database/sharedPrefernces inside the application data folder.