1) The document describes the steps to build a calculator app user interface in LiveCode, including adding buttons, setting sizes and positions, adding labels, and formatting text.
2) It explains how to group button interaction code into a custom "operatorPressed" command to change the border color when buttons are clicked to improve the user experience.
3) The final step is to update the mouseUp script for each button to call the operatorPressed command, allowing one line of code to handle the border color changes instead of duplicating code.