Hi Joe, technically yes, you can use Profile Attributes to store the values your visitors entered. Try following:
1. For every field that you want to populate automatically, create profile attributes.
2. Setup an activity for the page with form and create an offer which reads values from profile attributes created in step above. For the visitors who are coming for the first time, retrieved values will be empty so all fields should be empty.
3. In the offer-code, create an event-listener on onChange event. Link below on W3C website shows you how it works.
Tryit Editor v3.5
4. In the function pass text field values as mbox parameters by using mboxUpdate() or adobe.target.trackEvent(), depending upon the version of Target library you have.
5. Populate profile attributes corresponding to all mbox parameters.
Hope this helps,
Rajneesh