Is this easy to set up please?
There is no setup. Just put it around your neck the magnetic section of the strap will keep it in place and just press the button to turn it on. Instructions are simple and benefits from charging before first use.

What is voice feature for this massger?
The intelligent voice broadcast system, you can adjust the settings without having to take it off.

One (the small) end of the charging cable fits into the massager. Can I plug the other end into a computer?
Yes, you can. Through the USB outlet plug it into a computer

Is it loud when the massager is on?
There is no extra loud noise other than the normal sound when working.