Wiimote+ as far as I know needs some extra code, meaning it will not automatically deliver better sensor values. They have to be grabbed separately. I haven't further looked into it.
I don't own Wiimote+, but it should at least work for getting the accuracy of a standard Wiimote.

That pan is always 0 is how the Wiimote works. Pan can only be detected by additionally interpreting a sensor bar and the IR camera, otherwise it only delivers 2 dimensions of angles (Wiimote does not know in which direction you place your TV just by reading the sensor values, so it cannot know its pan either).
The calculating of a Pan however is to what I have read not very accurate and can lead to wrong values quite easy.
I haven't looked into how to do it in detail.

Accelerator values and angles are mixed. Actually the Wiimtoe does not deliver angles but just accelerations It is possible to extract the angles when adding all sensor values and then being close to 1. In this case it's possible to calculate tilt and roll out of the acceleration data. And that's also where the angle jumps are coming from. The acceleration data changes sign at certain positions, and this will is forwarded to the angle calculation routine.
The classic Wiimote delivers pretty inaccurate data. The feeling of good Wiimote handling is usually done by the game.
There is a reason why they released Wiimote+.


There was some headtracking stuff done by Puppeteer working just fine. I helped out with some code parts of my own old try and also wrote a version without using a shader.
Puppeteer's code is easy to understand and easy to use, so I did not recreate another headtracking script. It can be found somewhere in the Lite-C contributions.