How can I update content automatically every X hours?
This can be completely driven by Views &amp; Views System Message module.

You can create a block view for node content of type XXX that has an added Filter Criteria Content: Updated date with the Operator set to Is less than or equal to and the Value type set to an An offset... of "-5 hours" Value. That will get you a block view of content XXX that was edited more than 5 hours ago.

The last part, the alert message, can be added in the Header area by selecting the Global: System message type and setting the parameters to your liking. Once the block view is saved, you can add the block to whatever region you feel most appropriate.