Short answers (I may add more later if I have time):-
1) No. Use a safety tester - automated or otherwise - for electrical safety testing (EST). But yes, the medTester* does EST (and much more).
2) No. Those modules are nothing to do with EST.
3) Yes and No. Use whatever loads - internal and/or external (modules) - are required. Individual ESU service manuals usually (or at least
should) make clear which loads are required during testing.
In times gone by, some ESU service manuals may have made specific reference to the 454A, and which loads
etc. should be used (some may even have also mentioned the medTester). Manuals usually also lay down step-by-step techniques (or checklists) for testing. Some are better than others in this regard, but I recall that it was hard to lay down
generic testing procedures for ESU's. That is to say:- some had specific requirements. That did not matter too much when considering an individual setting (where only one type of ESU was being supported), but could be "fun" when many different ESU's were being looked after in different locations.
Lastly, you might enjoy
this YouTube video if you have a half-hour to spare (it includes the 454A towards the end - where it is referred to as "old school")!
* If I have whetted your appetite for the medTester ... be aware that they only operate on 115 V (or, put it this way, sadly I have never come across a 220 V version).
