1. None of the HN knockoffs can really clone Hacker News because, for one thing, it's missing everything in the original HN's code. pg mentions that there's a missing "secret sauce" that ties it all together. That, and you really need to have some sort of heavy involvement in the community before you try to start it, so you'll need someone of pg-level importance to start it. Specializations could be started by very knowledgable HN users in their field but very general implementations would need an all around "ideologue." EDIT: I don't know if you're already aware of this, I'm just explaining because the way you wrote it appears as though you may think the Arc code is packaged with a full implementation of HN.

2. I don't think this would be allowed via the HN Search API...that's a lot of content.

3. This is a cool idea, but how would you get people to participate and add content to what is essentially a ghost, rather than just come back here, where there's news? I also don't think it solves the problem HN is currently facing. It merely puts a bandaid on it until we get back up to 2013 level volume.