Fly... Correct way to put it on, as so many do not appear wearing this correctly

[Father Bill]

Fly plaids are an unusual accoutrement, but if most are wearing them... well, when in Rome, do as the Romans do.

I would never pin it through to the jacket for the exact reasons you state. I would use a good solid brooch to weigh down the front, and use solid safety pins at the shoulder, under the epaulettes and invisible as pinned from the bottom up.

White gloves are tiny. Stick them in a pocket and if the majority are wearing them, then pull them out and put them on. As Padre to the Legion, my white gloves are always in my uniform jacket pockets along with a few poppies to use as required.