How accurate is my German?

The good news: I was able to understand perfectly what you were saying without having to read the English text at all. However there are a LOT of mistakes, both large and small, which Insel has addressed already, and I'd like to add that you should consider carefully whether "haben" is always the best verb for what you're saying. And while there are word order issues throughout, the last sentence in particular needs a complete re-work.