Hi,
2/ It seems as though the NBN terminator can be accessed by NBN/ isp somehow;you previously described this as : " NBN appears as an (long) Ethernet connection all the way to your ISP " .....can you elaborate on this at all?
The NBN CPE/Terminator equipment is remotely managed by the NBN. The fact that connections between you and your provider are going over fibre and there's all sorts of multiplexing etc. going on is not something you or your provider worry about - it's fully managed by the NBN. Eg. The NBN box/CPE/NTD provides a fully managed tunnel through which you choose with your provider what goes over it. If you were to get an internet connection from an ISP, and you wanted to share this with several computers, you'd still use a router of some sort (the same way you'd set up a cable modem connection these days) and plug this into the NBN box. Think of the NBN box as providing 4 ethernet and 2 phone line extension leads between you and your chosen providers (correct me if I'm wrong people.. I vaguely recall 4/2 port config in spec).. The service provider etc. cannot see anything outside of the services they provide to you on it.. they just plug their end of the virtual extension lead into their equipment as you do into yours.