Do we have a functionality in Windows 8 where I can set an Alarm or a Reminder (with recurrence!!) and forget about it (and the OS will do the rest)? Or do I need to create a background task to do the work?
It is not hard to schedule one event but I would not want to schedule a whole set of recurrence events.
The calendar is already doing it, can I tie into this mechanism?
You can use Scheduled Notifications but there's a limit of 4096 of those, so the recommendation for a recurring task would be to use a MaintenanceTrigger. A couple of things to be aware of:
A maintenance trigger will NOT fire if on battery power, but the notifications are buffered so when you're plugged in again you'll receive them.
There's up to a 15 minute window from the freshnessTime in terms of the actual notification being triggered, so keep that in mind in terms of scheduling. For instance, if you set a notification to occur at noon, it might not hit until 12:14:59.