So the OEU will be permanently based in California??
It would appear so, but this would seem to make sense given that it allows the 'squadron' (not sure 3 aircraft officially constitutes a squadron) to directly tap into the knowledge-base being worked up by the US and international fleets that will also be based there.
The OCU is for new pilots transitioning onto the aircraft. By 2019 the UK will already have a trained cadre of pilots flying with Sqn A, so there shouldn't be any problems with initial carrier integration. And I'm guessing the RAF/RN will still be passing pilots through the Eglin training pipeline prior to the OCU being stood up.