you cant use root explorer to its full potential without rooting.
you should be able to odin back to froyo, but read through the threads to make sure you get to bootloaders right, because if you dont, you will hard brick your phone
you cant odin icbinb or trigger. those are only cwm flashable. once you successfully odin back to kb5 or kc1, look in krylons final cwm thread and move the two files to the right place and then you can flash one of those roms. for more information about the cwm flashable or odin roms, got to the bible thread in the development section
If I helped you, the thanks button is very much appreciated.