[josteink]

An interesting point made was to avoid using custom domains for the login emails

That's horrible advice. That sort of attitude taken to the extreme means we shouldn't be using DNS for anything ourselves and put everything in Google's (or Amazon's) big bag.

Should I redirect my customers to facebook.com/company as well in fear of someone taking over my DNS?

The lesson from this whole charade is to not trust something as crucial your DNS to untrustworthy companies like Godaddy. We've heard the horror stories before and we keep on hearing them again.

Relying on Google, a company with no direct end-user support and no emergency hotline to secure the most important thing you have, DNS, is even bigger madness. I've been locked out from a Gmail account before. It took me weeks to get it back, because Google has no support.

So yeah. Get a proper DNS-provider, and don't dig yourself deeper into the hellhole you're currently setting up.