1. Here are all RSS feeds known to the search engine as of some point in 2023: https://downloads.marginalia.nu/exports/feeds.csv -- it's quite noisy though, a fair number of them are anything but small web. You should be able to fetch them all in a few hours I'd reckon, and have a sample dataset to play with. There's also more data at https://downloads.marginalia.nu/exports/ , e.g. a domain level link graph, if you want to experiment more in this space.

2. It's a constant whac-a-mole to reverse-engineer and prevent search engine spam. Luckily I kinda like the game. It's also helpful that it's a search engine so it's quite possible to use the search engine itself to find the malicious results, by searching for the sorts of topics where they tend to crop up, e.g. e-pharama, prostitution, etc.