What are you using? Pop or exchange.
If pop, the server settings are under advanced.
If you are using exchange the setting isnt there since it wont delete it from the server unless you delete it.
Question 2: If you are using exchange the emails will be in your outlook when you go back to your office and on your ipod touch.
If you are using pop set the advance settings on your outlook and ipod touch to leave a copy of the message on the server server for a few days so both can download a copy.