Can I just say that the smiles aren't fake? I genuinely think it's nice to smile at people, and so do other Americans. Now, it's a whole other thing if it it somebody being fake. Americans aren't being fake, they're just being friendly. The politeness is also not meant to be fake etc. We do it because it's friendly.

I'm not lying when I say I'd like to help with something, I'm not lying about anything. We will tell you the truth. But at the same time in America it's normal to be polite and to not be super direct.

At your office, you just need to be clear and to the point. Any extra words won't help them understand what you mean. I know that it is normal in America to be polite and add extra words, but here that is frowned upon.

Next thing, don't take anything personally that they say, or the facial expressions they make, or the lack of emotion they put out. When I first started living and working here I found it difficult because I felt like I couldn't ever gage my coworkers' reactions about things. They probably already have a pre-judgment of you because you are American. I have experienced this judgment. Just be direct and stay confident and you'll be ok.