When a read receipt is set up in Outlook, does the recipient always get
asked, or see the request for the receipt?
I believe that the recipient has full control over read receipts; whether
his client even responds at all, or notifies, or accepts without question.
Is there a way to track but have them not see it?
Not really. There are third party solutions which rely on passing the email
through their service and adding web bugs, or even going to their web site
to view the email, as a web mail. But, again, those depend upon the
recipient being a willing part of the process. He would have to go to the
web site to view the message, if that is the manner of tracking, or allow
his client to access remote servers to fetch images, in the case of web
bugs.
A recipient who does not want you to know if he read your message can foil
anything you try to confirm the reading. OTOH, if you are in an enterprise
environment, and this is job related, I expect that you can compel employees
to allow such things as a condition of employment.