Do you have a little more information? A link to the lesson and the error code would be very useful. Have a check of the following How to ask good questions (and get good answers) for a little detail on how best to set up a question and details of code formatting for the forums.
Without the error it’s hard to say. It looks like a sensible inversion of the initial suite. Have you double checked the content of the sentence itself?
Logic in this style might benefit from a single if statement followed by elif clauses as it’s a little more efficient and also makes it clear to the reader that this flow of logic is grouped together.
No. The not negates the condition gpa >= 2.0. That means if the gpa is, for example, 1, then gpa>=2.0 will return False. The not then negates that to make it True.