Related question, has Anna's archive been thoroughly filtered for non-copyright-related illegal material? Pedo, terrorism, etc. I've considered downloading a few chunks of it but I'm worried of ending up with content I really don't want to be anywhere near from.
Download everything, we know that laws don't apply when you do it on a large enough scale. Not legal advice.
The team that curates it is very dedicated and wouldn't do such a thing. The least of reasons being they don't want the heat from it.
I'm not sure what other forms of information is illegal beyond CP. In the US, bomb making instructions are not illegal. In other dictatorships or zealous religious regimes, information about democracy or works that insult Islam might be illegal
How might you inadvertently download illegal content while searching for legal content?
This is a really strange question to be honest you could ask this literally about any download let alone simply torrents of documents.