Show progress bar
Show a progress bar for the task, let the user define a "Measure" (which represents how many things need to be done to fill the bar), and can then enter "Progress" (the number of things done so far) to show how much of the task is completed, to be visually represented in the progress bar. If you want to track % of task complete, set the measure to 100 (use as default?).
If a checklist is added, then offer to use the number of check-list items as the "Measure", and the number ticked checklist items as the "Progress".
Current Progress field would then become status.