1. Try to flash the latest stock rom with odin
2. I was once like you, can not restore my backup through cwm. Then I found out that thw cwm backup didn't include the preload folder. That's why made my S2 got a bootloop. And nothing that I can do to bring back my nandroid backup.
3. About your efs folder, try using GS II REPAIR that can be downloaded in playstore. Or you also can search in XDA for tools named EFS PROFFESIONAL. Worse become worst you will not get your original imei back, but you will get a generic imei (00499xxxxxx), at least the phone can work again normaly....
Good luck mate