1. Is impossible to damage the IMEI on U600 with NsPro.
2.NsPro can write IMEI without any problem on U600, If the NVM area is OK.
3. Patch is needed only to repair phones damaged with UST.
http://www.nsdongle.com/forum/index.php/topic,4543.0.html
http:///vbb/showthread.php?t=429512
4. Using patch file, you can repair IMEI on U600, E490 with NsPro.
5. Yes. After using the U600 patch, if you flash the phone with a different firmware, the IMEI will be damaged.
6. Yes. SPT box (latest version) can repair IMEI on any U600 version (damaged by UST)
Good for them.
SPT= repair solution for phones damaged by UST