Regarding ATMs (advice from a fellow European who has been to the US a couple of times):
I don't know if German banks have the same rules as Danish ones, but just in case they do... don't use an ATM unless it's an emergency!
Use your VISA card instead (most places take them and you really should get one if you don't have one)!
I found out that if I wanted to withdraw cash from an ATM I had to pay and extra 3% of the amount withdrawn to my bank back home in Denmark. Whereas if I used my VISA card I didn't pay anything extra (same as with buying things over the internet). Although 3% doesn't seem like much it quickly adds up.
Now, since our VISAs are debit cards, we can't get cash back from stores, so to obtain cash I would just pay stuff (like groceries) for some of my US friends with my card and they'd give me the cash instead. That way I'd always have reasonable amounts of cash on me without paying the extra ATM fee.
Cars
Americans really love their cars... just be glad that you're in a large city. My first visit was to a town a bit further south from where you are, Huntington, WV, and boy oh boy did they love them some pick-up trucks!
Another thing about about cars (and weather) that you're not going to experience, but I'll mention it anyway since it fits in with your observations about the US... people in LA seem to be mystified (and terrified!) of this thing called precipitation... more specifically, rain.
I watched in disbelief as a drizzle caused the entire freeway system through LA to slow down to a snail like pace. A trip that on any other day would take 20 minutes on the freeway, now tooks us 3 HOURS (I'm not kidding, the trip really took 3 hours and 10 minutes from "home" to where we were going - Santa Monica to Inglewood)!
They just seemed so unused to this strange phenomenon that most of them didn't know how to drive on a slightly wet freeway.