The iPad is not intended as a multiple-user device. While it can obviously be used by more than one person, there is no way to set up user accounts, as you can with almost all desktop and laptop computers, or other protections that would, for example, allow different users in the Mail, Calendar and Contacts app, or allow you to select which apps a given user has access to, other than the limited controls in the Restrictions. So you'll need to think about how the iPad will be used and whether you would need to protect some data from your sales rep and vice-versa. If you do, having separate iPads would probaly be best, or a lightweight laptop such as a MacBook Air.
You might find the iPad User's Guide helpful for learning more about the operation and settings:
http://manuals.info.apple.com/en_US/ipad_2_user_guide.pdf
Regards.