Disclaimer: While I like writing, I don't run a news site.
- Where does the information come from that gets posted?
Insider information if you're a big news site, from bigger news sites if you're a smaller one.
- Which news outlet is generally the first, has the most 'breaking' news
Mostly, the news giants. Think CNBC, CNN, etc. As far as I know bigger crypto news sites like CoinDesk still are mostly minutes/hours late compared to the giants.
- Do crypto journalist just monitor press releases, and write articles from there?
Mostly, especially if you don't have the connections to get early access to events, yes.
Theoretically, if you were to start writing news articles about crypto, where would you look to find breaking stories?
Everywhere. Especially when starting out, the likeliness of you out-competing the bigger sites(in terms of speed) is probably next to impossible, so where you can probably excel is the quality of your articles. Try to beat them in terms of depth of information.