Hit ENTER after each Tag to add it to your post; Numbers in parentheses represent the Tag's usage.
When you edit a Task, typing something in the body will not enable the Save button. You have to type something in the Subject.
Also, FWIW, instead of having the red "Delete" button right next to the Save & Cancel buttons, how about moving it to the far right? This would give it its own space, similar to how iOS organizes buttons that do different things.