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It is correct that our Regulatory Information Report 41117 version 11 refers specifically to NCC 2019. This will be updated at the next review. Meanwhile our technical people advise that It is not really the year of the NCC that matters, but the test method that is referenced.  NCC 2019 Amdt1 and NCC 2022, as will NCC 2025, require group numbers to be determined in accordance with AS 5637.1. and critical radiance flux to be determined in accordance with AS ISO 9239.1. So given that the referenced test methods in NCC 2019 and NCC 2022 are the same we don't anticipate any change when RIR 41117 is reviewed. 

The ABCB Housing Provisions don't specifically deal with damp-courses under timber frames. The assumption is that they will be used in brickwork or under concrete slabs. However, it can be a useful precaution to place a damp-course under the outside wall of a timber frame that is seated on a concrete slab. While problems rarely arise if no damp-course is present, occasionally slabs are subject to edge dampness. At WoodSolutions we have no particular preference as to the type of damp-course to place under timber but suggest you seek one that complies with AS-2012-Waterproofing-membranes for external-above-ground use.

Supplement no. 5 to Australian Standard 1684.2-2010 for non-cyclonic areas tells us that in N1/N2 wind areas 190 x 45 MGP 12 rafters @ 600mm centres will span 5.3m. That's for a single span (supported only at each end).