Figured I'd pitch in here, since I've spent a lot of time looking over LVVTA's standards for wheels, brakes and spacers recently.
Most of those points are all highlighted here: https://www.lvvta.org.nz/documents/standards/LVVTA_STD_Wheels_&_Tyres.pdf
Granted, that's dated 2016, but I don't see any of these points being laxed, and if changed, would expect them to be tightened.
1. It can, for pressed steel wheels. However, for cast aluminium wheels: see 2.5(2) a: the spacer is designed to fit only one stud configuration.
This is clarified in the notes: ‘Configuration’ means, within the context of 2.5(2)(a), that whilst a spacer can be of a multi-fitting design in that it fits varying pitch circle diameters, it must be of a type that will fit either a four-stud wheel or a five-stud wheel, but not both. Spacers that will fit both four-stud and five-stud wheels must not be used in any situations.
2. There is a method is pretty clearly spelt out in 2.5(1) f: be set-screwed or attached by another secure method to either the wheel or hub face;
3 and 4, I think that's pretty spot on in 2.5(1) e: be fitted as to ensure the wheel locates snugly over the hub spigot so that the hub carries the weight of the wheel assembly instead of the wheel studs, or where there is a mis-match between the hub spigot and the wheel centre, a close tolerance fit center bore locator must be provided
5. I'll just nitpick on this one, it's 6.5 turns: 2.4(4) b, i: in the case of a 12 mm metric stud or bolt with a 1.5 mm coarse thread pitch, 6.5 turns OR in 2.4(4) c "in the case of an unmodified hub assembly, not less than that originally provided for the fitment by the original vehicle manufacturer." , but given that you've spaced it out, I'd say b would be applicable.
This is all from the LVVTA standard, though as myself and may others have found, the interpretation is entirely up to the individual certifier, so what one certifier may say is acceptable, another may not.
In particular your local guys notes about using a heat resistant adhesive, some might pass that, and others might not. And then whether you get pulled up on it for a WoF is another story.
As your cert guy says, since you already have a cert, for spacers, it wouldn't be worth going in for a re-cert providing you meet all the criteria above.
But in terms of other modifications to your car that vary from it's initial certification:
What does your cert say in regards to your wheel size? Unless it's stamped OEM, most will specify a diameter and width (but oddly never offset, or tyre size)
With regards to brake calliper changes, that also would require a cert as per: https://www.lvvta.org.nz/documents/suplementary_information/LVVTA_LVV_Cert_Threshold.pdf
See section 8-1, as it doesn't list a calliper change there.
How that would be proven given that it bolts on would be another topic, but figured I'd bring it up.
But you can fit those larger rotors, as I'm assuming they would be "the same size as the OE rotors; and catalogued aftermarket items for that make and model of vehicle (and can include cross-drilled and/or slotted types)"