Moving Your Galaxy Between Disc Version and Steam Version?

Hello!  I've been playing Spore on the disc version since I was very young on a used computer that I got from someone else.  While it's been super fun, I would like to have my creation's author set to my name rather than a default.  Even when I change my PC name (and Windows user profile name), the default remains the same.

I have been considering using Steam (since I also own the game on there) to reinstall the game and go online again.  However, I still have almost all of my creations since around 2010 saved on this computer.  I have copied the local game save files twice on a flash drive (a second copy in case the previous copy did not write correctly), but I am still nervous to go through with the reinstall.  I plan to drop my original local save files (game saves, pollination pack, etc) back into the Steam version of the game once I reinstall, but I worry about doing something wrong.  What would be the right way to go about this?

I also worry about the future of Spore.  If EA ever removed Spore from Steam or Origin, would people ever be able to play it offline again, or will it go the way of Darkspore?  Using my disc version, I have had the safe feeling that since it is unsupported and is unable to connect to servers anymore, that EA will never be able to render it unusable.  With the Steam version, I feel like there would be reason to worry, because the game would now rely on Steam in order to be launched.  It would no longer be independent of any other software.