If the API does not use versioning or document changes, your only option is to use defensive programming and good error handling to figure out what breaks.
I believe its custom in some parts of Germany to use an article before the name. In North Rhine Westphalia (West Germany) I've often heard people say "Die Jenny, Der Thomas", etc when referring to people
Before you spend time building an LLC, find three clients. Then find three more.
In my experience too many people get distracted with secondary things such as building a website, printing business cards when they don't have any potential clients.
I prefer FOSS because it focuses on creating something good instead of something that focuses on extracting as much money possible.