You can easily create a segment based on contacts who visited a page and didn't submit a specific form to be used for a followup email.
Regarding capturing entered but un-submitted data you can likely achieve this with some custom javascript and an AJAX form post but I would personally not recommend it. If someone chose not to submit a form then they decided that they didn't want you to have that information. At most I think storing that data for informational purposes in a custom object would be ok but to use it to begin engaging with that contact would be rather intrusive and would probably upset that contact.