SPH-M900_CL14_STOCK_FIXED_with_CJ05_SBL.7z contains the linux kernel, /system, /data, and everything else. it's the whole package. if you were to jack up your phone to where it wont even boot up, you can flash with that file and it'll completely restore your phone to the way it was out-of-the-box.
ZE10.2 is just an enhanced version of the linux kernel. It replaces the stock linux kernel that is on SPH-M900_CL14_STOCK_FIXED_with_CJ05_SBL.7z, and nothing else.
you can definitely have both on your phone, and right now, that is the best option.
you are only rooted when you have Zefie's kernel installed.
i dont really know the differences between cl14 and cj05 except that cl14 improves upon many things that are in cj05.
before you flash with anything, read my guide, http://www.samsungmomentforum.com/rooting/how-to-flash-to-ze08-back-to-stock-kernelremove-system-apps