...

That will change in 8.1.2++, btw. "ndc" will use a socket, not signals.

Will 8.1.2++ allow - selective reloads?

yes. "ndc reload vix.com"

- selective cache cleaning (clean this zone ONLY from my cache)?

no. the cache won't have zone boundaries until 9.0.

...

I always put a zone up on the master before I send in the registration. If the slaves take a day or so to catch up I can live with that.

Depends on whether whichever NIC in question demands that *all* listed NS are ready for the domain, or only one, right?

that would be bad policy, since it would not reflect operational necessity. i.e., the zone fundamentally "works" if ANY of its nameservers is working. therefore that ought to be the only test done by any NIC.