Hello and Welcome! I’ll do my best to help provide you some info, or at least direct you to the best way to go.
No, currently the mesh works only via LoRa. Although, @mc-hamster has a vision for a future version that would create a mesh through BLE.
BLE
I believe the answer to this is no, there is an API being used with protobufs to communicate via client and device. You can find more information in the docs.
If by this you mean what devices support the Meshtastic firmware, you can see our supported devices here. If you mean something else, forgive me.
If you’re on Discord, we have a pretty active group (including all the admins/developers) and you can get quicker responses there too. Feel free to join!
Thank you very much! Love how far you’ve come with the project. Looks like the beginning of understanding the BLE interface is here
I’m glad for asymmetric cryptography you are leaning toward Ed25519 (per your Encryption page). I was planning Elliptical Curve (EC) for many reasons, and Ed25519 is EC. This will be very important for higher level capabilities.