Renesas CS+ for CC vs for CA, CX vs e2 studio
The main thing to know is e2 studio is for the American market and CS+ is "else."  If you expect support to help you, I recommend sticking with that. 

I personally hate how Renesas does that, but otherwise love their products. 

By the way, when you get started, check out their "Applilet" (aka Code Generator, AP4, and I think even a few other names that I forget offhand) but it's actually a really cool utility for driver generation. It will generate all your peripheral setup code for you in minutes and allow you to get right to your application code. If you've never used it, find and go through a tutorial on it first. There are some on Renesas website and the rest of the Web. 

I am using it for RL78 to great success.