FTTC install questions

My street cabinet has recently been upgraded ready for FTTC so I have been giving some thought to what will happen during the install process. Can anyone answer the following questions for me?

I currently have what I believe is a LJU3 master socket recessed into the wall with the BT line and an internal extension entering the socket through the wall behind. When BT fit the new NTE5 will this be fitted flush where the existing socket is located or will it require a new box on the wall?

Once the engineer has done his thing and left is there any (legal) way to bypass the splitter and get the VDSL signal onto the extension? I know that BT offer to install a "data extension kit" but I imagine they'd only run it along the top of the skirting board which I'd rather avoid as there is perfectly good cable buried in the wall.

The engineer may be able to convert the extension socket to master and fit the NTE5 there. Depending on the quality of the extension cable you may not see any speed reduction, but it is a caveat.

The BT engineer for my FTTC install tested speeds at master / extension 1 / extension 2 with varying speed results (25 / 30 / 32), so he converted extension 2 (which was the original master when phone was first installed 10 yrs ago) back to a master.

TBH, I'd rather keep the master socket where it is. I know in the short term I might be sacrificing a bit of speed but I only need it to get above 3Mb to see an improvement.

In the long term I'd like to terminate the VDSL next to the master socket (shortest possible distance) and then run a length of CAT5 to take the Ethernet to the router but I'm not in a position where I can start lifting floor boards ATM.

I currently have what I believe is a LJU3 master socket recessed into the wall with the BT line and an internal extension entering the socket through the wall behind. When BT fit the new NTE5 will this be fitted flush where the existing socket is located or will it require a new box on the wall?

Unless you can excavate the existing backbox and fit one of the plasterboard types, then no, the engineer won't be fitted flush. The new VDSL faceplate filters make even a recessed NTE stand out a fair way.

The data extension kit is only offered as wall mounted, and will be cleated rather than stapled.

If the extension cable is of a decent quality, and has spares, then the engineer *may* be able to juggle things around.