RE: Formula
Formula audit allows you to track the cells that contribute and lead from a formula.
So choose a cell that has a formula that is not working correcly, or one that you want to find more information about.
Then on the Formual Auditing toolbar (VIEW > TOOLBARS> FORMAUA AUDITING), choose from SHOW PRECENDENT (contributing) cells, or SHOW DEPENDANT (relying) cells.
Arrows will be drawn to the relevant cells so you can see which cells are affecting or being effected by this formula.