Interesting question Kyle. I took a different approach to a similar problem.
I calculated "Length of service" as such:
DATEDIFF ('month', [Hire Date], Today())
I don't think you want to be creating separate spreadsheets manually, so tableau can help you there.
As for your rehire date, you'd have to think of the logic and I haven't had the time to go into your workbook to work that out. Your comment was made ages ago, so let me know if you are still needing assistance with this.