Test/Quiz based website advice

I'm going to build a website (not for profit) to help pilots learn and stay current with all the rules.

Preferably, I would like users to be able to randomly take quizzes without logging in. But if they do login, then they can track their history and get feedback on where they could use more practice/study. Eventually, I would like to evolve the system to automatically start asking harder questions as the student/pilot progresses.
NOTE: Pilots progress through licensing stages, Private, Commercial, Instrument, Instructor....and I would like to have the system automatically start asking them the next level of questions once they are proficient.

I have thousands of questions and answers, and am looking for some guidance as to the best route to do this. I use HostGator, and haven't been involved in website backend work much since 2005. (I ran a phpBB forum in early 2000s)
I would be happy to use a WordPress based site, and will either learn the necessary skills to do the programming (if its basic enough), use a tool, or pay someone to help do this. (If the cost is reasonable!)

Any thoughts or advice?

Thanks
Chris