But you also asked for whether those stereotypes colour* my impressions when I meet someone from the US. (*Thanks for recognising that US English isn't the ONLY version!)
My response is to state that I'm unsurprised when I meet someone who conforms to most of what I've written, but I'm also pleased to acknowledge that many Americans don't conform to stereotypes.
For example, I met a guy (through this site) who was visiting the UK for the first time. We corresponded a great deal and I eventually gave him a guided tour of Paris (on a day trip from London). He lived in the Rocky Mountains (Lake City, Colorado) and his attitudes seemed 'stereotypical'. (He didn't even attempt a single word of French in Paris, not even a simple 'Merci'. I got the impression that he just assumed that US English ought to be used everywhere in the world). Throughout his stay in the UK he wouldn't go into a pub, as he was convinced that the beer wouldn't be to his liking and that he's probably get attacked anyway!
But a few weeks ago I met a US couple (from Nevada) who had only arrived in the UK an hour or two earlier. They immediately sought out a traditional British pub (which is where I met them), ordered British beer and (after enquiring what is was!) 'toad in the hole' for lunch.
I was unsurprised when the first guy met many stereotypes but I was delighted to meet the couple who didn't. (I used to run a railway station, where I met many American tourists. The vast majority were happy to immerse themselves in British culture but there were still a small minority who repeatedly, and very firmly, protested "We don't do things that way in the States"!).
Chris