App: memento

1. I have created a bank book with fields Receipt Payment Balance

What formula I have to create for Balance field to show,
Balance upto previous entry
+Receipt field
-Payment field
=Balance

2.
Certain fields I need to hide from display in list.

1. On app start getting My Libraries. I need my Group to show on start.

4.
Libraries be sorted on the basis of
Date Created Asc, Desc
Date Modified Asc Desc
Alphabetic
Manul
Frequently used