Optimized CyanogenMod 12.1 [JDCTeam] build 20150817

I have just install Optimized CyanogenMod 12.1 Rom by [JDCTeam]. Runs smooth, no lag, but encounters one problem. Sometimes cellular signal is lost, then I open cellular setting and choose prefered network again then the signal returns. Anyone has the same issue?
Also I'm still a newbie, so can anybody show me how to root with this rom and install SuperSU?
Thanks,