recall an au pair of mine telling me to say "thank you" after I sneezed and she said "bless you". She was surprised I didn't know that rule.
I grew up being taught to say excuse me after sneezing and the other person in your company says ‘bless you’.
I’ve never heard anyone saying ‘thank you’ after they sneezed.
The smoothing of skirts/dresses/coats is something I do.
Never heard of adult friends being called ‘auntie/uncle’. The first time I heard this was as an adult and a black colleague constantly spoke about all her ‘aunties’. I eventually asked how many sisters her mother/father had and she explained that all their friends are called ‘auntie’ and ‘uncle’.
My grandmother taught me things such as giving up my seat for an elderly person, holding doors open, sending thank you notes (these days I send texts!).
I teach my own kids these things as they arise and presumably they watch me as my eldest seems to do things I do from copying me.
I’m strict with table manners as bad manners disgust me - things like using a napkin, asking for things to be passed instead of reaching over, elbows on the table, cutlery when finished.
I agree with the poster above who said that etiquette is not as important as being polite, making people feel comfortable and having manners. For example, debating the correct term for a toilet/bathroom/loo is nothing more than trying to categorise people into class systems, which is something I find amuses insecure people.