Not really. In this case it would be best to submit a "Tell HN: Billing is down at the Gandi domain registrar" and provide details in the text. People that have accounts on that site would know where to log in and test.
Your call. They get a lot of emails and often have a backlog. If people find they can log in OK then it may get flagged, otherwise I'd just leave it. Perhaps not many people log in Sunday evening.
Not really. In this case it would be best to submit a "Tell HN: Billing is down at the Gandi domain registrar" and provide details in the text. People that have accounts on that site would know where to log in and test.