ECMAScript (JavaScript) syntax. Other flavors like PCRE, Python, or POSIX may differ slightly, particularly around named groups and lookbehind support.
Yes — the search box filters by token, description, or example across all categories, and you can also filter by category (Anchors, Quantifiers, etc.).
They're solid starting points for common cases but are intentionally simple — for example the email pattern isn't fully RFC-compliant. Test against your real-world data before relying on them in production.