Well....
Windows 8 is pretty clever. You COULD just clone over to the SSD (newer cloning tools do the alignment and such) and on first boot it should say "Detecting Hardware" and you should be good to go. Of course, this doesn't necessarily mean that it will activate, as there is a change in hardware. And it also means you're dragging over all your rubbish with it.
Given that you only want to put certain parts on the SSD though, I would recommend a fresh install. Your best bet would be to get a legit Windows 8 disk without a crack/key as you already have a key. From there, there is a registry key change that you can do to make Windows 8 think its an upgrade. Its the same with Windows 7.
Just change:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\OOBE
From 1 to 0
Of course, as far as licensing goes, you must KEEP all of your license/upgrade keys as proof of legitimate upgrade path.
You could install Windows 7 without activating, and then install Windows 8, deleting the Windows 7 partition during its installation. That would also increase the amount of writes to your drive.
And as for moving unnecessary files to a normal HDD, if you have it installed side-by-side with your SSD, just go into your user files and right click on each folder (e.g. John Doe -> Documents, or Music, or Videos, etc.), press the location tab, and change C:\ to whatever drive the other HDD is. That will move your documents and stuff to the other drive. Feel free to ask for more information on this.