Hello,
1. this problem is usually happening, when swashplate servos are not configured precisely in regard to centering.
Please try to set the head according this guide:
http://manual.spirit-system.com/index.p ... d_GeometryIn less common cases it is due to a very bad CoG. It might be good to verify if it is off.
2. Very often it is helpful to change rudder servo arm. You can find if it is OK from rudder end-points. If you can provide the values for left and right sides or 4ds settings file I can let you know. It has big impact on rudder performance overal. It is very important to make sure that mechanics is moving really smooth with zero friction. The most new kits require a ball reamer otherwise it can take months or years to wear the ball linkages.
3. This can be result of some wrong settings. For example if you will set too high Rotation rate in the Sensor tab while your Cyclic Ring limit is too low. Then model is not able to mechanically achieve required rotation fast enough. There are parameters such as Rotation Rate, Flight Style and Cyclic Feed Forward that can make behavior a lot different. In default settings behavior should be much more linear than with VBar. Spirit is not using any Expo, while VBar has default around 25 and even around 50% for tail.