kidyounot | nicholas' "Teach Me Some English", part one (Reply)

i need to ask couple of questions even google can't answer.

a) is there a difference between 'lucky' and 'fortunate'? if so, what is it?
b) is there a difference between 'pillow' and 'cushion'? and what is a 'cushion pillow'??
c) why do americans call autumn 'fall'? i mean i can see why, but why would someone change the name of a season in the first place?
d) is it 'americans' or 'american people'? is there a difference? which one is better? does anyone care?

also, looking for the difference between 'elevator' and 'lift' (i mean, i know they are the same thing, i just wanted to know which one was british and which was american), i came across a long list of words that are different in british english and american english.
well, i once wrote 'mum' somewhere, meaning to shorten 'mother', and someone apparently got very confused and they went all "WUT'S A MUM LOL IS IT A MUMMY OR SOMETHING'. and i go "uh... i meant mother." "LOL THATS MOM THEN" "oh... okay, sorry for not being clear". so ever since i have been spelling 'mum' 'mom'. BUT GUESS WHAT. i found it in the list, and mum is the british spelling, which means that i didn't just make it up for no reason, but IT DOES EXIST! so i'm happy. i will probably return to spelling it with an u now, just because.
because i want to impress my english teacher by using a lot of british english words because that's what they teach us in school and so i will look very... studious. and that's also why i'm reading shakespeare at the moment but that's a whole different story.

so yes. please teach me english. thank you!