Yes!
I would buy the Kinect for your Xbox but not a modded controller as you will get suspended if you play with a modded controller.
Kinect
There is no such thing as a wii kinect.
You can buy XBox 360 and Kinect Bundles at Amazon and on ebay.
Yes, you do not need to buy a kinect if you already have an x-box
No it doesn't. You have to buy special kinect games to use the kinect.
Yes, but if you want to get all technical you could say that kinect is the system and the kinect sensor is, well, the sensor. But if you buy the kinect, you are buying both.
Some people buy both, but you should probably buy for the system you already have because they are only optional equipment for the Xbox 360 and PS3
No the Kinect is something separate you can buy if you choose to.
If you already have the Xbox 360, you can just buy the Kinect bundle console which saves you more money. Kinect bundle works in Xbox 360 with both 4GB and 250GB memory. You can also buy an Xbox 360 which already comes with a Kinect bundle. You can't play Kinect without an Xbox 360 nonetheless.
Amazon have some great Xbox Kinect bundles, but demand is heavy so you are advised to buy early.
No. Just hook the old X-box with the new Kinect.