Running through the piece in order:
It's wrong to refer to the test socket as the master socket. The latter is the entire NTE5 (or other) unit and, importantly, contains a surge suppressor and ring capacitor. The test socket is just a BT socket hard-wired to the exchange pair, useful for testing but
not something which should normally be used for day-to-day connection as it leaves the circuit unprotected.
It would possibly be worth mentioning the potential benefits of disconnecting the ring wire and the use of a filtered face plate.
It might be worth mentioning that it's better to avoid running phone extensions parallel to mains wiring.
Repeated disconnects: There's a BT PDF file at
http://freespace.virgin.net/adsl.test/doc2.pdf which sets the threshold at ten times in any hour.
In my experience, interleaving tends to be turned on when a line is considered unstable, eg as a result of repeated disconnections. BT tend to be reluctant to switch it off again in these circumstances. If anyone has a higher target margin than the 'normal' 6db, they may well struggle to get interleaving turned off.
Connection problems, especially those which affect some websites only, are often caused by incorrect MTU & RWIN values. It might be worth detailing the procedure for setting these values despite your reservations.