There may be other opinions, but I would recommend staying with what you know -- in this case Java. The "pain" of learning C++ just isn't worth it. (And this coming from a mentor who knew C++ and had much more C++ experience prior to starting this mentor gig and having to learn Java). Also, if there continue to be FTC teams that you are drawing students from, you have the advantage of having incoming programming team candidates with Java expertise.
I mentor both FRC (2992) and FTC (8991 and 10337) teams for programming using Java, and we have found the advantage of having incoming FRC students with FTC Java experience to be a great jump starter.
I recommend you check out
https://wpilib.screenstepslive.com/s/4485 which is the documentation for the controls and programming from last year. AFAIK the 2017 version is not yet posted (though there is some 2017 beta info at that same site).
Whether you use C++ or Java, you will likely be using Eclipse. It's not that different from Android Studio. Installation instructions at the above website are reasonably easy to follow. Its actually a bit easier to setup for Java than C++.
The API tutorial for Java is pretty decent. You will see a ton of similarity w/ FTC API for accessing hardware and driver station. The IterativeRobot base class is very similar to the OpMode base class for FTC.
While it may seem a bit more complex at first, I strongly recommend you look into the "Command Based" programming model. The "Robot Builder" tool that comes w/ the API is a good way to jump start into Command Based programming. My first year as a mentor, the team had lost all of its programming resources so we were essentially programming rookies. We switched that year from C++ to Java and started off doing IterativeRobot but switched partway through build season to Command Based as it makes Autonomous programming much easier (it enables a base class called CommandGroup similar to LinearOpMode from FTC). Command Based also allows easy multitasking for your robot, with each "subsystem" able to operate fairly independently, making your code easier to implement and troubleshoot.
Finally, make sure you take a look at the SmartDashboard tool and API. This is similar to (but much more powerful than) the Telemetry functions in FTC.
I took a quick look at your FTC code, and it looks good. I don't expect you to have any issues making the FRC transition.
Good luck and have fun
Mike