Re the pilot; you say earlier he was a 'spec N', which would indicate he had done the specialist Navigator course, and elsewhere there is a hint he had earned his DFC as a Nav as well. Although a crossover to pilot was unusual, but not unknown, it could be that he was actually quite inexperienced as a pilot (I'm not casting aspersions here) despite his number of hours, and certainly his total Stirling time was relatively low. Do you have any indication of his previous service record?
Re the landing light, again it would be unusual to switch the landing light on except in extremis - it is a very good beacon in its own right for marauding night fighters. A landing light at 500ft can be seen an awful long way away - just try standing well west of London on a reasonable night and see how many aircraft you can see with landing lights on on their approach to Heathrow! Using the runway lights/goosenecks on their own was quite standard practice - again perspective was/is everything, and it is quite straightforward to make your approach in that way.