Permanently Save Data

I developed a timesheet interface using Excel. I am creating an setup-like phase for when the time sheet is first opened which determines file path names and what not. I basically I have 2 questions which basically tie into each other:

1. How can I ensure that the code only runs the first time the workbook is opened?

2. Is there anyway to store the data (for example the pathname to a certain file) without storing the actual data on a spreadsheet for it to be pulled from? I guess I could use a seperate file but I'd like to avoid that if possible.