Simple example of Timed background task for Store app?

You've already found the sample code for this, and it demonstrates everything you mention (except the every-minute debug mode, which doesn't exist). If you are having problems with your specific code please post a minimal repro to your SkyDrive which demonstrates what you are doing and where you have issues.

Syntax for Registering is in the Register the background task to run section of the Quickstart, as is syntax to check if the background task is already running. You would call these together as you want to check if the task is already running so that you don't restart it again if so.

--Rob