Sorry I can't really offer any advice on the job in question, but I would advise you to change the stop cock valves; or at least put a separate one in that turns all the supply off, without having to go outside.
When we moved into our house, over 12 years ago, the main stop cock valve was part of a lead pipe and had virtually seized. We could still turn the water off by turning it off outside - but it was well worth the cost of getting a plumber in to fit a new stop cock valve under the sink.
Another thing as well - we've just had our kitchen sink and taps replaced last week and the guy that did the job explained that he'd fitted separate valves to each tap, so we could isolate them if we needed to replace a tap (they're the ones where you just turn it with a screwdriver to turn on/off), so these might be an option??