"A new customer service system": could be the myntlhome which is only available in Celtic area at present, which allows customers to view and amend there account online. Not aware if this is being rolled out nationally though, but it does appear to be quite popular and has rec'd good feedback.
"Bills changing for the better": will probably be the new billing system (Harmony) which is currently being implimented nationally and will hopefully be completed by Aug/Sept, I believe. It will mean that everyone will receive one bill for all services and ntl staff will be able to action a customers query from any area in UK.
"Big changes to the way we provide your service": not sure on this one but it could be a combination of different things including the above, email server upgrades etc.
Hope this helps, my apologies that I couldn't give a definitive answer to all your questions.