I can answer the first 2,
1) Doesn't matter, whatever floats your boat. Sometimes I do, sometimes I don't.
2) Don't read too much in to the stuff on blogs about what's appropriate and what's not. In this case I assume you have been reading A Suitable Wardrobe? In Australia, just wearing a tie to a wedding these days is a feat in itself for many people. I certainly didn't wear a macclesfield for my own. FWIW, I think the plaid is a good wedding tie and I've sold quite a few for that purpose alone. With a white shirt, charcoal suit and black shoes would be preferable.
This is exactly what I wore on Saturday night together with a white linen pocket square - clean and sharp!
What the heck is a spitalfield?