Thanks for the response. :) By calculated value I mean it just uses the now() function to time stamp the checklist item (updating the 'date&time' timestamp field) that's been checked through a rule on the checkbox control.
I'm using a list because I may want to add/remove columns of data later, depending on growth/scope of the form. But I want a centralized place to maintain this list through SharePoint hence why I stored my secondary data there. In fact it's actually three different lists (basically a matrix) that the form will pull from depending on choices made in the form. I have the form pulling the data the way I want to which, in itself, appears exactly as I would like it to - it just doesn't function as I would like it to (i.e. the saving of the 'checked' and 'timestamp' fields for later viewing/updating after being submitted to the Sharepoint Library).
I'm open to suggestion on a better way but I'm trying to keep the form as dynamic as possible with as little code as possible, so making a change to the sharepoint list(s) will feed into any new form that's created (using the published template file from the SharePoint library), without affecting previously submitted ones. I know what I'm trying to do with the form is far from complex compared to how some use InfoPath so I'm sure there must be a way to do this. I looked at the link provided by Hilary for CAML queries and I think that will let me update a sharepoint list with changes from my form, but I don't actually want to make any changes to the datasources in SharePoint using my form. They will remain basically a read-only stream as far as the form is concerned, my intent being to update them directly within the SharePoint list manually as required, since the values (i.e. my 'checklist items') will not change very often. That said, I'm trying to keep maintaining the list easy for my work colleagues so they will not require knowledge of InfoPath or XML to make necessary changes to the SharePoint list(s) themselves, when it's actually required.
After looking through qRules a little bit.. it seems the 'copytable' feature may help me do what I need to (making a copy of the read-only data source into a mirrored table in the form I can then manipulate, as mentioned here: http://claytoncobb.wordpress.com/tag/qrules/), but I'm trying to avoid using code and taking this route if at all possible...
I'm also confused on your paragraph:
Gennady Vanin (Геннадий Ванин, Новосибирск):Create a (.XSN) form template with desirable fields (controls with underlying data fields) in Infopath Designer, publish it into the form library (for maintenance issues like versioning, relinking, etc.) and instantiate multiple forms with data (they are usually .XML files but it depends) based on one template (this again depends, it is possible to have many), store and open them. I would do the latter in a document library separate from form library storing form templates.
Could you explain what you mean in a little more detail, step-by-step so I can see if this might work for me?