What kind of security does cabal have?
Right now, very little. Cabal should be treated the same way you would treat an IRC channel: generally private, but discoverable + readable by sniffing local network & DHT traffic.
We're trying to get the core platform and networking solid right now, and have lots of plans & ideas for security in the near future, especially around end-to-end encryption and peer-to-peer permission models.
What's the plan for media embeds?
How do I get chat history when I connect the first time?
To get chat history, you need to be connected with at least one peer who has the history. But it doesn't matter which peer you connect to, since everyone in a cabal has the full chat history locally.