I login to Fios website, home-> services->internet, click on Parental Controls, it shows me another network's devices. GE Smart Plug, Echo, Chromecast, Galaxy that I don't have.
I will give to you my two cents.
You only need to use their NAT router if:
You have Fios TV One (or Fios One TV - if I got that so close but not quite) AND OR if you need support from Verizon.
Support will end at the ONT if you use your own NAT router.
and -> If you use your NAT router, they can't see inside of your network.
#2 Not sure how to solve it but it seems that they have the networks backwards. They can see yours and you can see theirs instead of the other way around.
I don't follow you input, but I am using the Fios router. I now see 'Nicolas MBP' and other devices via the mobile app as well. If you want my two cents, this is because I subscribed to the converged mobile / Fios login, and now their system is corrupted. But this is a major security flaw, cross network information sharing.
"Nicholas MacBook Pro" is a place holder, is a piece of text that shows there as a suggestion, an example of what a hostname should be labelled. If you try to put text in the hostname field, you will see how you can overwrite that text and I can also tell is a place holder because its color is more greyed out, just not enough too be noticed as place holder, its color is too dark for a place holder text so it can be confused as actual name of a device. I just noticed this whole thing right after we activated our Verizon router. (Verizon should change that place holder for something less confusing like "Example: Joe Macbook/Desktop".
That's it. We are safe. Cheers!