But yes, we're not officially launched yet and the website is going through a rewrite to offer more clarity, thanks for the feedback.
Re: seed nodes: they are running the same software and work the same way as regular nodes, the only difference is how they're deployed (with a public IP address vs. behind a NAT). But yes, a little bit of asymmetry is needed because of NATs/IPv4.
Re: properties: mainly we need to provide encryption and self-certification to enable a similar user experience as GitHub/GitLab/etc. on a an untrusted peer-to-peer network. Additionally though, Radicle offers a level of censorship resitance and disruption tolerance that GitHub cannot offer.