You have a lot of questions so I suggest that first you get a little electric orientation at the following web site: www.ezonemag.com On the left column click on "FAQ" and you will get answers to a lot of your questions. Now, you said you think you have a Great Planes 75 motor. I went to the Great Planes web site and the only thing I could find that may relate to that is a motor system with the catalog number of 'GPMG0755' which has a S-600 motor and according to their blurb will handle an airplane up to 50oz. ? The motor voltage is 7.2-8.4. Don't think you will be happy with a 6 cell battery, better to get a 8 cell battery at least 1000-1200mah. The 8x4 prop is the suggested prop for that motor but that depends on the airplane. A 20amp ESC will be insufficent. You need at least a 30amp ESC. Check ESC specs to see what you may want. Great Planes has ESC's. Their ESC's have a safety for arming the motor which prevents the motor from running when you first turn on the receiver. With their ESC you have to move the throttle to full and then back to idle before it is armed. It also has a plug if you want to disable the BEC feature. As far as motor comparisons, there is none. There is no standard for electric motors used in the hobby. The FAQ's will give you info about the numbers used for electric motors. That will be all of the homework for you tonight. Good Luck!! Above all get experienced help with the airplane and assistance in learning to fly. Should be a local hobby shop that can advise you as to a club that will get you started in the hobby.