Many things about the new Freenet are very different, however the original Freenet had a reputation system called "web-of-trust"[1]. The new Freenet's reputation system will be a generalization of this.
> where you initially buy keywords from freenet.org, like a domain name purchase, and then other users add or subtract from your rating.
Not exactly buying keywords, you can use a donation to "bootstrap" a reputation, this is done anonymously through an RSA blind signature. There will be other ways to do this too - but a donation is simple, and obviously benefits the project.
> The new reputation mechanism must integrate with the subscription multicast in order to limit the abuse of the network. I'd be interested in a description on how this works.
This is largely addressed by lower-level mechanisms although the reputation system could also play a role. Each peer keeps track of its neighboring peer's behavior, abusive peers will be disconnected over time. See [2] for a description of part of this mechanism.
[1] https://freesocial.draketo.de/wot_en.html
[2] https://github.com/freenet/locutus/blob/3e5a31780f235e04f7b2...
If I wanted to setup z-library on freenet, an example where reputation could be greatly enhanced by users of the service yet at odds with the legal system. Could the governed outweigh the influence of the government using the reputation system? Sorry for the silly information wants to be free argument, I know you've answered such questions ad inifinitum.