We've found answers for:

No, the QX side frame has the mounting holes drilled into the frame for the fixed axle plate.

Link to this FAQ

The QX comes with a fixed axle plate with only 0° of camber, while the QXi comes with the option of either the adjustable axle plate (0° or 3° camber) or fixed axle plate. Also, the QXi has more feature options than the QX.

Link to this FAQ