How Can I Know The Registered Devices In My GCM Application Cloud (List Devices)

1- let's Say I've Create A GCM Application In A Google Apis Console ...

How Can I List And View All The Devices Are Registered In My Application Cloud

To Perform An A Random Action Like Send A Push Notification to them ?

2- Should I Create A database to Store The Registration IDs Returned By Registered Devices If I Use My Own Server Like (Asp.net)