To be sure we're on the same wavelength...

For item 2 - checking for device status - When you log in to your vPanel and click in the Features tab at the top, you should see the word "Devices" in the dark blue menu bar. If you click on the word Devices, you should see a table with the headings Username, Contact, and User Agent (there's also Domain and Expires, but those fields are empty). If your device is properly registered, your phone# will show up under username, and the Contact column will have "sip:{yourphone#}@{your_ip_address}", and the User Agent will say something like PAP2T. If your device is not registered (meaning, you won't get calls), you'll see a message "You are not currently registered to our servers!" When calls were failing, were you registered, or did you have the Not Registered message? (I never thought to ask you if the Line 1 light was on or off on your ATA. )

For item 3 - the Network Preferences option. If you click on the Features tab in the light blue, then click on the Preferences word in the dark blue bar, the choices on dark blue menu bar change. You should see the option for Network Preferences after you click the Features tab, then the word Preferences. If you still don't see it, put in a ticket--there could be some add'l configuration needed on your account.

I don't think I asked--do you have a number entered in the 'failover' feature, or do you failover to voicemail? At this point, it's more of a question of curiosity, because the calls not showing in your logs does suggest that they never even made it to Voipo's call processing servers...