Eassys stats requirements

Background: I'm a teacher, sometimes I ask my students to write a piece of essay(I normally have a word count requirement) and upload to my Google Drive. Since I have quite a few students, I need some automation to help me get a general idea of their homework completion statistics.
The software tool should be able to get the latest homework from my Google Drive, which are nothing but essays, so they are just texts.

Detailed requirements:
1.List the students who have not submitted their homework, if there's any.
2.Do a word count on every homework, show me the average word count of the class. Also, highlight students whose essay is 15% less than the suggested word count.
3.The number of unique words each student uses, as a measure of the richness of vocabulary.
4. User input upon prompt should include the list of students, the suggested word count, and datetime to start the automatic homework status check.
5. The software tool doesn't have to have a graphical user interface; a command line tool is fine too. But I'd appreciate friendlier user experience, so GUI is definitely a bonus point. Private message for more details. The bottom line is the user interface needs to check the validity of user input. I don’t want to see the software crash unexpectedly.
6. The code should be readable and easy to maintain. I expect the software to be thoroughly tested.
7. A detailed ReadMe file should be included, along with other documentation.