An engineer will not come to your house or change the sockets (this is rare nowadays).
They will just post out a Homehub 5 to you. You connect it in the same way you currently connect your router ie socket - microfilter - router
You can use an extension, it may cause slower speeds and some disconnections. This is the same as with standard ADSL.
There is certainly no NEED to use the main socket, it will work elsewhere... As I say, it may be slower / less reliable. So you can use it in the study if you don't mind the compromise.
It is one router. No extra devices.
Edited by ukhardy07 (Fri 10-Apr-15 21:59:15)