First question: I happened to check my public IP on my computers this morning....

One had the correct IP assigned by Vodafone (121.73.xx.xx) but the other computer had this public IP 66.249.82.94. As this is not something I check regularly I have know idea how long it's been that public IP for this computer.

A who is lookup shows it as being:

Hostname google-proxy-66-249-82-94.google.com Network AS15169 Google Inc.

City United States Latitude/Longitude 38.0000,-97.0000 Carrier T-Mobile Route 66.249.64.0/19

Another Who is result shows this:

IP Address 66.249.82.94 Hostname: google-proxy-66-249-82-94.google.com

ISP: Google Inc. Connection Speed: -

City: Sydney

Country: Australia

State: New South Wales

Latitude: -33.86785

Longitude: 151.20732

Timezone: UTC +10:00

Local Time: 07 Mar, 2017 02:26 PM

Proxy: No

ZIP Code: 2000

Area Code: 02

IDD Code: 61

Weather Station: Sydney (ASXX0112)

Usage Type: (SES)

Search Engine Spider Domain Name: google.com

Mobile MNC: - Mobile MCC: -

Mobile Brand: -

Elevation: 69 meters

ASN Number: 15169

ASN Name: Google Inc.

Is it something that Vodafone had done?

Both computers go through my D-Link DIR-880 L router, and the router has the 121.73.xx.xx public IP loaded. I never usually turn off my router or Vodafone Cisco modem. but after I had rebooted the router, both computers now show the correct Vodafone assigned public IP address.

BTW I have not had any problems with my Internet connection at all with this strange IP address...

Second question:

Is IPv6 available on the Vodafone cable network in central Wellington yet? If so how do I make sure I have IPv6? And how do I set it up/configure it if it is? 

I have read all the recent threads in the Geek Zone Vodafone forum and read the Vodafone help pages (not much help) and Vodafone community threads, which appear to say not yet as there are 'still issues with IPv6 on the Cable network according to the last post there. (IOW Coming soon, since sometime in 2015...)

I'm on Vodafone cable in central Wellington, and have one of their Cisco DPC3008 modems plugged into my IPv6 capable router.

When I go to http://test-ipv6.com/ I get the result below:

Your IPv4 address on the public Internet appears to be 66.249.82.113
Proxied, Via: 1.1 Chrome-Compression-Proxy

Your IPv6 address on the public Internet appears to be 2001:4860:4801:4014::4d
Proxied, Via: 1.1 Chrome-Compression-Proxy

Your Internet Service Provider (ISP) appears to be GOOGLE - Google Inc., US  

Since you have IPv6, we are including a tab that shows how well you can reach other IPv6 sites. [more info]

Your browser has real working IPv6 address - but is avoiding using it. We're concerned about this. [more info]

We have detected that you are using a proxy. This means we are testing your proxy server, not your computer.

Good news! Your current configuration will continue to work as web sites enable IPv6.

IPv6 Connections using DNS work; but literal IP addresses in urls do not. These are rarely used on the web today.

Your DNS server (possibly run by your ISP) appears to have no access to the IPv6 Internet, or is not configured to use it.

This may in the future restrict your ability to reach IPv6-only sites. [more info]

PS: I generally try not to play around with network settings due to my (very) basic understanding of them and the likely hood I'll stuff them up. (and wont be able to fix what I have stuffed up)