Kitkat Rom + Safestrap For xt912 Verizon

Hi there i'm using motorola Droid Razr xt912 and its laggy with current orignal 4.1.2 Rom peoples suggest me to flash new Rom so fainally i decided to instal New rom so as i know safestrap is require for it so i already checked Shadows thread and Downloaded Sypder safestrap i chosef correct version for my phone right ? For Conformation i,ll add a screenshoot
And as i heared Kitkit is awesome android Rom i reduse less ram and as i heard Kitkit is suitable for xt912 so please give me a best rom for my droid razr
And i heard some time phone brick so what are the reason for brick so i can avoid these things to protect my phone if there is so
And why safestrap is required we cant install rom with orignal recovery??