There is no reason you can't add explanatory text to the status bar when using dropdowns. In any event, given the amount of unused space that would become available by using dropdowns, that space, too, could be used for explanatory text.
The problems with using formfield checkboxes include:
1. They cannot be used without macros for any calculations; and
2. Require additional code to ensure only one option is checked.
If you're wedded to the checkbox route, you could adapt the code I wrote for the content control version of the code in
https://www.msofficeforums.com/word-...g-results.html to work with formfields instead. A fair bit of re-working would be required, though (e.g. there is no generic FormFieldOnExit event, so you'd need to add an on-exit macro call to every checkbox in the form).