If I can offer an opinion: regarding payroll, keep as much information
as you can. Payroll is sacred- people literally live by it, and they
are VERY concerned that proper records are kept. A Fortune 500 company
is judged by its stock price; small and even medium sized companies are
judged by whether or not they met payroll.
My suggestion is to allow the spreadsheet to be as large as it needs to
be in order to keep highly detailed, accurate records. The LAST thing
you want is to be forced into a corner, where you have to say to a
state examiner of one type or another "I don't know what the payroll
data is for week x" just because the spreadsheet isn't a few columns
wider. When the sprdsht gets wide, just hide the earlier columns.
Keep the data- protect yourself and your company.
Pontification ends!