Your FCS2 will install onto a new computer just fine. Make sure you have serial #s handy and don't attempt to migrate anything. Make it a fresh start.
Media managed projects are the easiest to open because all of your media has been copied to a dedicated directory. I'd be shocked to hear that FCPX causes any sort of grief opening your project.
I upgraded to FCS2 to FCS3 without any issues. I'd recommend purchasing FCS3 so you have the latest "legacy" version in case you need to use it. Both FCS3 and FCPX will be able to live together in your applications folder.
If you're going to keep your old computer you won't be able to run FCP6 or 7 on both computers at the same time but you don't have to un-install it.
You're good to go.
Apart from the fact that the folks posting here know just as much about FCP X as you do....
Consider the fact that FCP X is not an upgrade, but an entirely new application. It is possible that FCP X will not read your older FCP project files at all. Then again, maybe it will.
You can't compare reading in projects from FCP 6 to FCP 7 as they essentially have the same architecture. I can load projects from FCP 1 into FCP 7 without issues.
There is no unregister or verification procedure for current versions of FCP. Delete it from the old machine, install on the new one. Done. There might be an exception where a serial number has been recorded as stolen or faked.