1. Traditionally in centerline/tandem airplanes the throttle is on the left.
2. No, it is not hard to transition.
3. Depends on where you mount the radios but putting them on the left prevents you from having to switch hands while flying.
Really, it will take you all of one flight to get used to stick in the right hand and throttle in the left and you will be surprised how natural it feels.
I just came back from recurrent simulator training and as a company check airman with authority in all seats I am required to perform some maneuvers from the right seat. Flying from the right seat with the yoke in my right hand and the thrust levers in the left just feels more natural despite the fact I normally fly from the left seat.