2. The license is not limited to the device but to your computer/account. If you change your controller (or use CDJ/DJM setup) - the license will apply. The only time you'd need to buy a further license is if you wanted to use the DVS side of things and use a timecoded CD in the CDJs.
I was surprised that the device doesn't have a hardcoded license and can unlock the software - eg if you sold the device on, the person buying it wouldn't need to buy a separate license. But in case like the above, having a separate license has it's benefits.