Part of the reason you're so confused is because you're asking the wrong questions, based on your experience with glow.
There is no such thing as a "more powerful motor." Motors don't make power, they transfer it. You can make any motor have any amount of power by increasing the voltage and/or increasing the load on the motor. Of course, motors will have their limits, and if you push them too hard, they will burn out. You may think of the battery as just a "fuel tank" but in fact, it's your combustion chamber too.
With electrics, you start by figuring out how much power you need to fly the plane in the manner you want to fly it. This is completely different from glow, where you crowbar the biggest engine you can into the cowl
YOU tell the motor how much power to make by adjusting the voltage (cell count) and prop size. With glow, the engine tells you how much power it can make, and you have to work around that limitation.
Now, people tell you to get the AXi for your Shocky because it has been proven to work well on that particular airplane. Its characteristics are that it produces large amounts of torque at a low RPM, which is ideal for swinging a large propeller, which in turn is ideal for 3D flying. In contrast, the Himaxx motors, due to their design, are low-torque, high-RPM motors that either need gearboxes, or are limited to spinning tiny props at high RPM.
There's absolutely no reason you couldn't put the right geared Himaxx on your Shocky and get performance comparable to the AXi. That's the beauty of electrics; there are literally hundreds, if not thousands of different ways to arrive at the same place, and they're all perfectly fine.
If you want reading material, pick up an issue of Quiet Flyer. Also check the FAQ thread at the top of the Electric General Discussion forum. There is also
www.rcbatteryclinic.com to check out. Be warned, though. This stuff takes time to learn. If you try to digest too much, you'll only make yourself more overwhelmed than you already are. I suggest that the best learning is achieved by doing. Go ahead and get that Shocky fitted out with the recommended equipment; don't take any poetic license just yet. See what goes into a successful power system, learn about Volts and Amps. You won't be sorry.