Can you limit user interaction on a PDF e.g. Read and Write only?

Yes, Owner Password is an advanced feature available in PDFpenPro beginning with v.6x and higher. Owner Password restricts user interaction with specific aspects of the document. Please note that "Owner Password" differs from "User Password." Unlike User Password, if you applied Owner Password, the user for a password would not be prompted for a password upon opening the document. The user can still open/ access the document. What is limited, are specific document actions e.g. printing, editing the document etc. To apply Owner Password, choose Inspector and click on the last tab with a lock. Enter your Owner Password and adjust your settings.