I'm not going to comment on alot of the points you've raised because the answer is mearly yes, no matter where you go you'll find people who stereotype people alot and think that everyone from one place is the same.
As for the language point you raised about niether language being more correct, alot of people view american as incorrect or lazy because alot of their spellings of words are just english with letters taken out to make it simpler. Another thing that annoys alot of english speakers is that Americans think they speak english, they dont, they speak american. They are very similar languages but they have been seperate languages for a long time.
If an American speaks american and claims they are speaking english then they are wrong and are speaking a warped version of english and visa versa.
As for the language point you raised about niether language being more correct, alot of people view american as incorrect or lazy because alot of their spellings of words are just english with letters taken out to make it simpler. Another thing that annoys alot of english speakers is that Americans think they speak english, they dont, they speak american. They are very similar languages but they have been seperate languages for a long time.
If an American speaks american and claims they are speaking english then they are wrong and are speaking a warped version of english and visa versa.