Im hoping there are some clever people out there that can tell me a bit more about these things and answer my questions.
Firstly, Id like to know exactly what they are, and who they are held by and who enforces them.

We have one on our house, and we would like to get it removed. It expires end of this year, but need it off about 9mths earlier than expiry. What are our chances of getting it removed? What is the process and how long would it take, roughly?