RX antennas are ziptied to the rear arms.
Use a fin to get better turtle mode. Brain3D sells them or you can print your own. A gopro mount will also work, this is just to lift the motors off the ground in the event of a crash because with a bottom mount battery the props can hit the ground while upside down.
Frontal impacts with the camera can cause it to shift back and knock the 4in1 connector off of the FC if you don't have a fixed camera mount, so I'd recommend printing or buying one.
I have 6 inch arms running 5 inch props.
Any issues with the camera sticking out so far? Currently building my first Floss and having the lens stick so far out is making me parinoid since I seem to break a lot of lenses.
Nope, not a single problem. Had one case where it went back into the stack and knocked my 4in1 connector off but that wasa crash directly into a flag. If you get a fixed camera mount it makes it a lot easier to prevent damage.