1. Excel undo stack clears off whenever a macro/function is executed
through the code. Can this stack be preserved? If not then can we write to
the Excel undo stack?

2. Is it possible to hook the Excel function dialog to display
function arguments help or function help description.

3. What is the best way to handle Excel busy exceptions that occurs
whenever a cell is in an Edit mode and at the same time the Excel objects
are accessed.

4. Would like to know whether there are any specific compatibility
issues that need to be considered while running the add-in on a multiple
Office versions

5. Is there any property for storing metadata in worksheet that can
also store objects as the CustomProperties can store strings only.

6. Is there any way to identify the idle time in Excel such that
processing can be done then.

7. Assigning cells formula property to an embedded formula throws
HRESULT exception. For example, if a cells formula property is set to
=SUM(MyUdf(),1) then COM exception is thrown (assume MyUdf() returns 1).

8. Installing the Excel COM add-in with "For everyone" option does not
write the OPEN key to the HKCU hive which is required to load add-in on
Excel startup. Is there any key in Excel 2003 like the "UserSettings" key
present in Excel 2007?