General :: Security Concerns About Rooting / Custom Roms

So after having seen that I could use CyanogenMod 10.1 to get version 4.2.1 onto my Tab, I've gained a particular interest in rooting my p3113. With that said, I still have concerns about security with custom roms;

-How do I make sure I am as secure as possible?
-Is it still safe to purchase with Google Wallet on the Play Store?
-What should I avoid in order to remain safe?

I know the "risks" involved in rooting a device, although following instructions will assure that such issues do not occure. So other than the actual security issues, I need no additional information