You can check the papers on the non-code repo [1] but an update to the whitepaper (4th draft) is in the works.
not sure what you mean by http interface discovery, thou. Each local node opens a readonly http interface (localhost:8080 by default) and a json api interface for cli and webui (localhost:5000 by default). gateway.ipfs.io simply a node that exposes it's readonly http interface.
The binary 'wire' protocol happens on 4000 by default. The discovery of other nodes happens by connecting to a bunch of known/configured nodes to bootstrap and asking them for other nodes.
yeah, if your device wasn't supervisioned before it would clean install - i guess but i haven't tried and/or checked otherwise if you can than reapply your backup.
(Edit to add: It's actually unclear if the non-pairing restriction gets applied when using this method, it doesn't seem to get listed in the profile details once on the device)
very interesting. i wonder if they have access to the gpios already. would love to try to connect it to my logipi fpga board and shell out complex computations to that.
[1] - https://en.wikipedia.org/wiki/Mill_CPU_Architecture