Last thing first: We currently use nsec bunker when users login using a username and password. But it hasn't been very reliable lately, so we're working on switching to a better solution. And, users can always login to their existing Nostr account through a Nostr browser extension on their desktop, or through the spring.site app on an Android phone.
As for your other questions, your city needs to be activated on our website before we can add anything to its merchant map. For it to be activated, it needs at least one ambassador to moderate and manage it.
If you would like to be an ambassador in your city, our Ambassador Concierge, Jason Hodlers (npub1693…4j0c), prepared a video for you to help you get started:
https://www.youtube.com/k8tD6Tnl-Fk
When you've completed the initial survey about your city, we'll set everything up, and add you as your city's ambassador. At that point, you'll be able to send us links to saved lists of your favorite venues, including all the places that accept bitcoin. We'll also be adding locations that we believe will appeal to bitcoiners (carnivore menu, seed-oil-free, raw milk, etc), but the "ambassador picks" will be essential to include on the map, as well.
Let us know if you have any questions!