You can do the tasks in any order that you want. They are to guide and challenge you but if you want to leave some out that is absolutely fine! Equally, if one task really inspires you and you want to do several versions of it - go for it! The tasks will remain available to you for two months so work at your own pace. That said, having the discipline of doing a drawing a day will reap rewards.
I have added some of my images and sketchbook images to show you how you might approach the tasks. Remember there is no right and wrong, approach to the tasks with an experimental, playful approach. Stay curious and see what happens!