What questions? Thousands. Just the first ones that comes to my mind :
What about...
- Jake,Tobias, Marco and Ax, The Blade ship and the One?
- Rachel's family...mother, Jordan, Sara, and her father?
- Jake's parents?
- Erek and other Chee?
- David?
- Crayak?
- Ellimist?
- Gonrod and Estrid?
- Gafinilan and Mertil?
- Ax's parents?
- Hork-Bajir planet?
- Chapman and his family?
- Illim, Tidwell and the Yeerk Peace Movement?
And many others. Maybe, I'm too picky, but there are a lot of unresolved questions...