Create your checklist. To reorder checklist items simply drag & drop them.
When the task form is saved, checklist is presented as to do list with small checkboxes:
Simply check the box when you've completed it, the task progress can be easily tracked this way:
If you need to know when the checklist fields have been created or completed - this information can be found under History:
If the task to-do-list requires other users involvement or may have different deadlines - it is more convenient to use subtasks: