Follow these steps::- 1st publish form to a local location,say My Documents,make sure b4 that u'll click on option of enable infopath to open in browser,and change security level to full trust,in form options.
Then keep clicking on next,add fields that you want to make visible in form library,and finish the publishing wizard.
Next goto Central admin,and enable infopath form services,in central admin->Application Management->Infopath forms services,click on upload Form template.
select the location of your infopath form locally and click on upload.
Next goto manage form template,just below Upload form template in infopath form services,select your infopath form and activate it to a Site collection where you want to use it.
Goto ur site,create a form library,and goto advanced settings of ur form library,and select allow management of content types and display as web page.
Then from upload existing content,select the form that you just activated for that site collection..make it default and try to run ur workflow.I think now u won't have problem in making the fields editable..
i would be glad to hear,if that works,otherwise we'll proceed further and try to make it work 4 u anyways,4 the time being try this and let me know.Have a good day