So far it looks good.
For the battery I would suggest a 4000-5000mah lipo (3 or 4 cell)
Do you already have a transmitter? If not I would suggest the devo 10 radio control transmitter
You did not include a camera, are you planning to stream directly from a gopro/ other camera onboard?
I would suggest our open source gimbal controller with this brushless gimbal, but its always better to first get the frame setup and flying and make sure you are confident before adding extra gear like FPV and gimbals as you don't want to crash with lots of extra expensive gear due to a silly mistake. So to start you should first get the y6 kit, get that built and flying, then start adding the FPV gear and gimbal.