It is the same everywhere around the world and fairly simple. You will have to use your Amazon.com account or, if you don’t already have one, create an account to process the payment. Kickstarter also made this how-to video: http://www.kickstarter.com/help/faq/backer+questions#faq_41759
The C.24 should work with computers via micro USB connection as a class compliant MIDI device. We also want to support Bluetooth to PC, but we need to finish all the work for iPad first, so at this point we cannot guarantee this will be ready by the time we ship.
We hope to support Android at some point. We just need to finish everything for iOS first. We can't give you any specifics on when or make promises that it will happen, but we hope to be able to provide support at some point.