What's up, Ryan. Hope you got good deal. I built 3DR's Y6 a couple years ago. Tons of fun - a mean flying bird. I have parts to build an X8 but just haven't gotten around to it.
I'm gonna go out on a limb and guess you are new to RC?
You stated you have an FPV Racer - did it come pre-built with a transmitter and all? Did you have to do and Radio binding, calibration, setup, etc? If so, What you will be looking forward to with this X8 will be similar. If the answer is no, and you have not had to do any setup, binding, calibration, etc, then this will be a fun little adventure for you.
If you're even semi-competent with computers and technology, and if you can follow instructions, this process should be pretty doable. There will be some trial and error, but you'll manage.
First some notes about what you got.
So 3DR sold this bird as an "RTF" system. It came with everything you needed to get flying - a pre-built X8 copter running Pixhawk, battery, and Radio. All of the programming and calibrations for Copter and Radio were done by 3DR so the buyer could, after some simple setup, simply charge the battery and go fly.
This bird is a little different than other RTF systems out there like Solo, Phantom, etc, as it used legacy RC technology in a DIY style package - It was no different than all the other DIY Arducopters out there running Pixhawk, it's just they did all the setup for you.
So all you have to do is do the Setup, Programming, and Calibrations that 3DR did, and you'll be ready to fly.
More to come...