All the driving motor cars had replacement ends as did 'some' of the NDM cars. However, the money ran out before the job could be completed, hence there are still ends with sticky tape. However, it is believed that this will be rectified when the 1992s go for a big upgrade in time for 2020 - a large package of mods. The first two-car unit is at Acton Works now as a prototype.
I am sure the first train was 51501+51701. One of those units (51701) had a collision on the South Ealing test tracks when it was new. I can confirm next week if someone gives me a reminder. This was not the first train in passenger service though. And the Jubilee 1996 got there first with the Northern 1995 later!
51501+51701 was the first train to be delivered.
51513+51514 was the first train in service 12/6/98.