You are not understanding how all of this works.
Yes, iTunes Match will allow you to have access to all of the music in an iTunes library from almost anywhere. However iTunes Match must have music in the iTunes library when the service is activated. If you activated the service on your new computer, and there is no music in the library, of course you will not see the music from the original computer.
As I said in my first post, your personal data from the original computer will not magically appear on the new computer. You must put it there by transfering it. iTunes Match is not the best way to do this transfer for music. Now, if you wish the music from the original computer to show up in the cloud you must enable iTunes Match on that computer as well and let the service complete its scan.
About the iPod: an iOS device can only be synced to one iTunes library at a time. When you connect it to an new computer for the first time all the entertainment media and apps will be deleted and replaced by what is in the new iTunes library. So, to make sure you have all your personal data, again, copy the entire iTunes folder from the original computer and place it at ~/Music/ on the new computer the launch iTunes.
