Do framing sentences work in Part 1 and Part 2 as well?
Part 1 rewards a shorter answer and Part 2 gives you a preparation minute, so the frame moves to the start of the long turn.
Partly. Part 1 questions are concrete, so a frame spends time you could spend on a second detail, and the honest version of a Part 1 answer is shorter. Part 2 comes with a preparation minute, so the frame belongs at the start of the long turn, where it can announce the structure you planned. The one or two rounding-off questions after the long turn behave like Part 3, and the cause, comparison and prediction frames work there unchanged.
One rule travels with the frame when you change parts: it has to match the shape of the question, not the number of the part. A why question in Part 1 still wants a cause frame, and a comparison question in Part 3 still wants an axis.