A quick word of caution with elapsed duration (edays) tasks. An elapsed day is a 24 hour period of time. If you assign a resource to the 28 eday task the resource will be scheduled to work 672 hours.

To your post question of "24 hour task calendar doesn't show a day" - a "day" to project is 8 hours. It is defined in File > Options, Schedule. If you wanted to use a task calendar representing 7 working day per week - you would have been better off creating a new calendar and making Saturday & Sunday working days - but only 8 hours per day.