Frustrating, but in the scheme of things...

Blues wrote:
Does the ReadyNAS still come with a 5-year warranty?

The RN516 does have a 5-year hardware warranty. Check these links:
http://netgear.com/images/pdf/ReadyNAS_ ... 700_DS.pdf
http://kb.netgear.com/app/answers/detai ... rn516-faqs

Blues wrote:
Can I use my old ReadyNAS Pro Business for backup as a ReadyNAS Replicate unit?

I have not yet tried this, but I think its possible that you could use your old ReadyNAS Pro Business unit as a Replicate backup of the RN516.

Blues wrote:
Will the ReadyNAS 516 permit me to have dual redundancy? I think that's RAID6 with two redundant drives?

Yes, RN516 supports dual redundancy.

Blues wrote:
If I use ReadyNAS Remote how secure is the connection? Is the data sent between machines encrypted? If not, will it work while I use a VPN?

ReadyCloud replaces the ReadyNAS Remote on the ReadyNAS OS 6 models like RN516 using FW v6.2.x.
On your old ReadyNAS Pro Business unit, ReadyNAS Remote is still supported.

Regarding encryption on ReadyNAS Remote, kindly read the ReadyNAS Remote-White Paper on this link:
http://www.readynas.com/download/docume ... _Paper.pdf