Spark - Case management & Calendar?
Spark should include Case Management, yes.  Whether it provides a "calendar" depends on what you need in a calendar.  If you need a report that shows upcoming deadlines in order of date, you can set that up within Spark.  If you want integration with your Outlook calendar or a website's calendar, that would require an extension, which isn't available with Spark.

However, Spark is a great way to see if CiviCRM meets all your other needs.  If it does, then you can always move off of Spark to your own CiviCRM instance and install the extensions you want.