Yes — 418 "I'm a teapot" (from the April Fools' RFC 2324) is included alongside all the standard codes.
Yes — search by number or by keyword (e.g. "not found", "redirect", "server error") and results filter live.
Yes — you can filter by 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, or 5xx Server Error.