Screen reader output when focusing on questions in a complex form

Hi folks,

There's a form with multiple question types. In addition to text fields, 
check boxes and radios, it uses push buttons that trigger modal dialogs, 
as well as input type="file" elements as ways to answer questions.

Let's say, I'm filling out the form with screen reader and move with the 
tab key. When I navigate to  a question that requires me to upload a 
file in order to answer it, focus moves to the <input> that triggers a 
file picker. Only the name and role of the element are announced on 
focus. The question itself (E.G., "Upload parent document") is not read.

  *      Is it necessary (from WCAG conformance standpoint) to have the
    question announced when the control that serves for answering gains
    focus?
  * If so, how do I implement the behavior? I thought of using Fieldset
    and Legend, as well as role="group" with ARIA labeling elements, but
    neither of these approaches seems to fit since they work with
    multiple related controls, not 1, as we have in this case. Using
    landmark role="region" is off the table, there,re too many questions
    in the form, and marking each question with region seems really bad.

-- The same question applies to the case where there's only 1 checkbox as an answer to the question. I'm not sure if grouping one element is sensible. Otherwise, screen reader doesn't announce the question when the checkbox is focused, only the name, role and value of the element.
Any guidance is highly appreciated.

Best,
Vlad
vkolp95@gmail.com