Glad you got it working again.
As to flashing. Yes, you can still flash your phone. The main problem you had was because of the Sprint customizations on your phone. Now that you are back it should work just fine. The PPCGeeks kitchen is pretty simple to use but OEMs can get you in to trouble now and then (the ones provided in the kitchen should work fine). Look to the sticky threads for any how to articles. I can't think of a good one at the moment.