You cannot directly upload files to the forum. Please note the listed file types of what can be uploaded--they are all file types for image files, not databases.
Reminder messages are possible. Essentially a script does a find for all records in a table where a "date due" type field matches specified criteria--such as all dates within 7 days of today or some such with additional criteria to keep the reminders from appearing more than needed such as more than once a day.
Typically, such a "check for reminders" script would be set to run from the "onFirstWindowOpen" script so that each time a user opens the file the script checks for and displays reminders.