WordPress suitable for my project?

Hi Community,

I’m trying to determine whether wordpress is suitable for my next project. I understand what wordpress does, and I’d like to know if it’s possible to get my project running without too much development effort.

The project is a simple online application to help students practice speaking English. Features are:

1. Basic form: A collection of prerecorded questions for students to answer.
2. Questions are in a variety of topics, and are organized in 3 types.
3. Each question will have transcript text, audio recording, hideable hints, and other meta data.
4. For a topic of questions, the application is responsible for randomly choosing a few questions from the topic collection and present them in a specific order.(Though random, application should be able to record whether a certain question has been practiced, and use this information to decide further random results, the goal is to practice as much number of questions as possible, not to practice a single one many times)
5. Students may choose to browse limited free content without registration.
6. Students may enjoy the capability of tracking progress, making notes, marking difficulty, see more free content by registering.
7. Students may choose to view questions (search) by certain criteria, such as their own difficulty rating, or notes.
8. Students may choose to purchase extra premium content (questions).
9. It’s very likely a future mobile app will use this application to serve contents in a similar way. This won’t be phonegap, but I’ll need the content to be available in say JSON format as well
10. Application will expand to other fields of English practice.

I don’t have a clear idea on how this could be done in wordpress, other than using ‘blog posts’ in place for ‘questions’. It appears that ‘comments’ can be used for users to record their own notes, and other metadata. But is it possible for a permission flag, to separate public comments and private comments (visible only to the commenter)?

For other functions such as a random choice of questions in a session, and others, I’m planning on developing plug-ins. But how long is this going to take? And are plugins gonna be a mess during version upgrades?

I’d like to know if wordpress is suitable for this project, and the required timeframe and skills to finish it.

Thank you.