Can you store a macro on the Desktop, G-drive or C-Drive

I've multiple questions here so i'll appreciate it if my questions are answered. =)

1. Is there a macro that possibly runs from multiple file location? eg. Desktop, G-drive or C-Drive.

2. If the cell format of an application form is shifted, how do i show that there's an error stating "wrong format" in the error worksheet after i've run it?

3. Set a default date format on my worksheets eg. 20-Oct-2007

4. The header tends to appear in the middle and not the top after adding a workbook to the end of the first workbook. Why is this so? can i bring it to the top?

Thanks for helping.