For your first quadcopter the runner 250 can be a good option, but since its release I think there are a few better options as the runner 250 flight controller is quite basic. Depending on your goals it might be a fun idea to build your own FPV quadcopter, possibly something like the ZMR 250. We will also soon be releasing a ready to fly 250 size kit that includes the FPV goggles too, and will have an APM flight controller which includes a barometer to manage your height automatically which makes things much easier for beginner pilots.
That said you should be able to mount the AirPro2 onto your 250 size quad with some Velcro straps, and mounting foam. I dont have one myself but it does not look too heavy. As long as its similar in weight to the gopro it should be fine to mount onto your quadcopter.
As for the wifi, that is something that I dont suggest you use. most R/C gear runs on 2.4Ghz and the camera wifi will interfere, and when you fly far away it could possibly block your R/C signal from reaching your drone.