I am new to data validation in Excel and would like to seek your advice on
the following items

1) For a particular column, I would like end users to enter 6 numeric digit.
I have tried to choose Decimal with min 6 & max 6 but doesn't work. Then I
use "Whole Number with min 6 & max 6" but also doesn't work.  What
validation criteria should I use ?

2) End users don't like to enter "Today's Date" by themselves.  I try to use
the formula "=Today()".  However, I believe the date in that cell will
change every time we open the spreadsheet.  Is there any easy way to show
the
date they last modify the spreadsheet ?

3) They would like to keep the column width to 30 and I would like to know
how to protect the width ?

Thanks