Currently, there are a few ways question accessibility could be improved. Noted some details below.

1. Since this is to be used within a page, the question title should be a heading 2 as most page titles are heading 1.
2. There is not proper form markup. Need to use <fieldset> and <legend> tags to ensure the wrapping question is read when the answer choices are interacted with via tab or other navigational keys.
3. After pressing Next or Go back, focus should be placed on the step currently selected. You can do this by adding tabindex="-1" on the <li> element I believe. This should work fine but might be worth testing to be sure.