The cable is included according to the brand. It seems to be a micro USB Logitech only speak about a 2.95 m 12-pin captive cable.

Is only compatible with the Rallybar. The plugs are different.

No, it can not be used as a stand alone mic. It is meant to be used only in combination with the Logitech Rally controller. @Digitec kindly update the description so people doesn't need to ask or make wrong choice as I did

No, unfortunately we do not have an extension cable for this product.