Lenovo a7000 custom rom problem?

I'm having a few doubts about flashing a custom rom
1)I did a backup using twrp and if I want to get back to stock lenovo ui will restoring to that backup bring me back the original firmware?
2)is the cyanogen mod rom having data connection problems in lenovo a7000?
3)which custom rom other than cyanogen mod is most stable having no major issues?