2. I agree with the beginning of your interpretation but I definitely don't agree that he is now sitting on the ground having a rest. All we know is that he is no longer running.
3. I agree with the beginning of your interpretation but we don't know that he had started running there before you reached the park. What time you reached the park is not specified. You might have been walking in the park since 4.55 or 3.20 or any other time.
In all your sentences, you need to put a comma after "John".
Student or Learner