There are literally hundreds of threads about these topics. There has been a lot of discussion over the years on the cap topic with regards to Neve, the search will turn up lots of info.
Re the input transformer yes you can swap for another but in my opinion the Marinair/St Ives/Carnhill have a certain quality that is part of the Neve thing.
For the output transformer the Neve has special requirements because DC flows through the primary, search for combinations of "Neve, Gapped, LO1166" etc.