1. no you can't do that
2. I'm not sure about
3. NFSFAN's ROM's are as good (imho)
http://forum.xda-developers.com/showthread.php?t=432487
4. after flashing the phone does not need to relocked...Only for warranty purposes would you need to relock your phone, when it is nessacary then just run .40 unlocker and flash back to the original stock ROM provided by your carrier...