If you use the 8khz rate they will whine but using the 32khz is silent. You can change it in the software.
Is up to you. If you are working on a close set which sound is very important then use the silent mode, if you are outside and noise is no issue use the 8khz mode.
Is it that easy, I got the impression that you have to tune the pid settings after switching? Fabien says in his videotutorial that he does not advice to use it yet...
I'm not an expert and I've never seen the M10 in person and I know someone from freefly even commented on here saying the motors were built by freefly but they look an awful lot like the Dualsky XM7015TE-5.5MR google the model number and you will see what I mean. That particular motor is 70mm in diameter which looks about right when I look at M10 pictures. So in my humble (ignorant) opinion I would not be surprised if they are using rewound Dual sky motors on the M10. And if they aren't Using the Dual sky motors (which is totally possible) I would say that if you wanted to build a gimbal for BIG cameras like RED with accessories or BMCC with big lens and accessories then then Rewound Dual Sky Motors will probably have the power. But like I said, I'm not an expert.
We did rewound dualsky (70-s) motors (100 turns 0.28 mm USSR wire) it does work with red. Can not say about the quality but for my opinion U8 is better to be on pan...