Looking to install an open fire with chimney grate etc. On the other side of this install in the room behind there are sockets on the wall, (telephone and a couple of double sockets) direcdtly behind where the fire will be installed in the other room. Are there any regulations around this? Cannot find anything stating that this wouldn't be allowed.
Any wall you can stick on wallpaper without it going brown (or smouldering !) will be fine for wiring.
Yes, but it seems to be too early to tell at the moment.
There may be a reason why fireplaces are generally against an outside wall or paired up on opposite sides of an internal wall.
I suppose that it depends to some extent on the material to be burned and the construction of the hearth, but after a few hours, the bricks in our fireplaces glow red hot.
The boxes behind the sockets will reduce the thickness of the wall. I have no idea how thick the wall needs to be, but doubtless your registered installer will know. 
