True, it's not clear yet. I've discussed some of this in the substackers post - higher configurable cost to post and comment, and staking (like you see on Sphinx Chat) are the basic parts of what I'm considering on this. I plan to begin working on these features before the end of the year so hopefully we'll both get some clarity there.

I've commented about this on other threads but the gist of how I'm thinking about this is: it's a relay network like bitcoin's mempool (I call it a newspool). To relay a message (e.g. a post or comment) on the network, users prove they've paid one of SN's wallets. Users can configure their newspool policy: which subs they want to subscribe to and relay, their dust limit (ie their personal Sybil tolerance), etc. It's more of a protocol than an API. Nothing on the blockchain although I might use block height for a rough time estimate. Users can then connect to their personal SN node with a client. There are details I'm omitting and details that still need to be fleshed out obviously (like what data availability looks like in such a system) but you're mostly up to speed with me.

This remains to be seen too. I take your point seriously. Other users like @calle don't want this either. I haven't implemented it for a reason. One point I'd like to add is the scarcity around invites would be artificial - more of psychological hack than an actual barrier. Hidden speakeasys are oversubscribed for a reason - the secrecy drives people to talk about them.

Also thanks for resharing those links (Shirkly and kuro5hin). They're super relevant and I'm still yet to read them fully.