I have published an app in the playstore for android , but i need some things to make it more perfect

a. I need the ability to adjust the character spacing inside a string as my app is about creating some font designs.
b. I need the ability to take a screenshot that is bigger than the active app area of 1920x1080 , ideally i would want for example to take a screenshot 500 pixels more to the left top right and bottom that includes the whole user visible screen and the outside of the frame
c. I need a way to ask for permissions to save to storage , i have of course checked the appropriate permissions checkboxes at the android build page , what this does do is give the ability for the user to manually go to the options>apps>permissions screen and enable the permission, by default when a user downloads the app from the store it does not ask him for any permissions (no such window pops up) and he/she has to do this manually every time.
Thanks