Re: "maybe around kilobyte of storage"
My estimate was per name. I wrote:
a name is a few rows in the database and maybe around kilobyte of storage
So a DB (or DBs) totalling ~10GB if both our estimates are in the ballpark.
Again, it's the registrars that deal with registrants over expiry, whois data, etc. They just push updates to the registry. The registry itself doesn't need a lot of staff to manage this DB since it doesn't deal need to deal with registrants directly for the most part; updates can be submitted via APIs. The registry doesn't need to run call centres, or provide a Web admin console for DNS or whois, etc. for registrants. Some registries handle escalated eligibility disputes, sure.
However, any such work has no policy-making implications; you can just employ staff that follow processes laid down 20 years ago to do it. Or out-source the technical stuff.