An old I Love Lucy episode comes to mind, it's got to be tough! https://www.youtube.com/watch?v=uZV40f0cXF4

I'M A BUS.

Not really, German here:
"Ich bin zuhaus(e)" -> "I'm home"
"Ich bin in der Bäckerei", "Ich bin bei der Post", "Ich bin bei den Großeltern" -> "I'm at the bakery", I'm at the post office", "~~I'm at my grandparents place~~ I'm at my grandparents" (or "I'm with my grandparents")

Home is a state of being in addition to a location.

One of my favourites to think about is "How are you?". Taken literally that question makes no sense. "How are you?" "Well one day my parents had sex and I sort of grew from there...."

If home is where your heart is, and I have my honey's heart, then saying "Honey, I'm home!" makes perfect sense.

Only a little.

Every language has some set of rules to how your supposed to construct sentences. Every language has a ton of exceptions to those rules.

The main thing that makes English difficult is that it's a kind of hybrid language. It's in the Germanic branch of the Indo-European languages but it borrows a ton of words from the Romance branch. The grammar is also a weird hybrid (for example we preserve grammatical gender in pronouns, like in German, but we've mostly dropped grammatical gender in nouns and articles, like in Chinese.

This is one of the simpler types of exceptions.

Consider the Chinese phrase: 好久不见 Litterally: "good time not see" But then someone explains that while 好 normally means "good" it can also mean "quite" or "alot".
So it's fairly easy to remember that it's generally translated as, "long time no see".

Those steps are pretty simple for a Chinese learner to understand. It's also not the hard part of learning a language.

I'm the law!

Absolutely. I'm an ESL teacher in Korea, and getting my students to use prepositions properly is a significant portion of my job. The difference between something like "He is coming to you." and "He is coming for you." isn't obvious at all if you think about it, but there are definitely proper and improper use cases for them.

I am away?