don't worry about getting your engine quite yet,for the price of the motor for that plane, you can buy yourself a www.towerhobbies.com trainer and actually learn to fly your nice looking plane you have there.there is a huge selection of training type planes for the novice flyer to chose from the tower trainer to the NEXTAR there all good to learn on some even come with basic simulators,there is even the mustang PTS thats do able.
the Extra is such a manuverable plane you will have a really hard time controling it.better to learn the basics first.
the engine alone for a 4st will set you back around 300$+or- depending on the brand.
with a trainer type package you will get your radio as well as a easy to fly plane,easy is a relative term, a smaller engine,consumes less fuel,cheaper props,etc... your club trainer will tell you all of this.