I'm probably only a couple days less newb-ish than yourself, but here's my two cents. (If I'm wrong about anything, I bet it will trigger a lot more responses than your original question did. So, you win either way!
1) I read the entire (current) Juicy ROM thread, and the entire flashing thread, but off the top of my head I couldn't tell you what SSPL and HardSPL mean. This shocking lack of knowlege did not
seem to impede me when I flashed my ROM and "radio".
2) There are some recovery techniques, but I'm guessing that if you manage to brick your phone to the point where it will not turn on, or make it into bootloader mode, then you are probably up a creek. My advice would be to not brick your phone.
3) I didn't have to re-configure a gosh blamed thing after flashing both the OS and radio. Hard resets can wipe out things
you did to the phone after you took possession of it, but the lower level carrier configuration seemed unaffected.
I'm on Sprint. I flashed Juicy 4.4 and the Telus radio.