Crystalyte motors

I plan on purchasing a 400 series Crystalyte hub motor and have a few questions I hope someone can help me with.
Here is some basic information will help with my questions.
The 400 motors are rated at 500 watts. I don’t think this means much because it is my understanding that they will handle much more than the rated amount without overheating.
So with that in mind here are some questions.
Would I be better off with a 406, 408, 409, 411, 412, or a 413 motor given that I don’t need to go over 25mph but I do want plenty of power for steep hills.?
In putting together a Li-Po pack would I get more efficiency from a 36volt 21AH pack, a 48volt 31.5AH, or a 72volt 42AH pack or a 72volt 21AH pack?
I know that Crystalyte makes a 412 and a 413 but I have no information on the speed they are capable of given different voltages and amps.
I would love to know how to calculate what to expect using different volt/amp combinations on the same motor with different winding configurations such as the ones I mention here.
I think a battery that does not need to exceed it’s AH rating will be more efficient, right?
I heard that batteries that produce high output compared to there AH rating are not as efficient as batteries that have a constant output rating that is close to their AH rating.
Here is some info I ran into that that I copied and pasted here that might help:
I upgraded it to 48V, which I consider essential, and would still like more torque, though the speed is adequate. I mounted this kit into an old 10-speed mountain bike. The 408 winding allows me to speed along at pretty near my out and out top speed on an old ten-speed bike. The 4011 winding is much slower, and it doesn't seem to have much more torque. Were I to do it again I might just get a single speed 409 motor.
Lessons learned, get all the battery you want to carry, at the highest feasible voltage. Coming from an engineer, remember that voltage is usually cheaper than current, i.e. it's cheaper (and lighter) to use a 409 motor at 72V and 20A than a 504 motor at 48V and 40A, for similar performance. You can do the math, but I already did and that's the message.
Resistance Readings for the different Motors between the motor wires:
406 --0.42 Ohms, 408-- 0.58, Ohms, 409 -- 0.70 Ohms
4011--1.0-1.05 Ohms, 4012--1.10 Ohms,

406 motor is the fastest Hub Motors Crystalyte makes, but will choke up on even small hills without pedal assist. It will deliver speeds in the 33 to 28 mph at 48 volts and 28 to 23 mph at 36V in a 26" wheel..

The Model 4011 Rear Single Speed Motor provides ample amounts of hill climbing torque and a safe comfortable riding speed in the 16-10 mph range in a 26 inch wheel at 48 volts and 11 to 6 mph at 36 volts.
The Model 4013 Rear Single Speed Motor is slower than a Model 4011, but has greater torque. The Model 4013 is well suited for utility trailers and adult tricycles where hauling a heavy load is needed.

The Series 5 X-5 750W Rear Hub Motor Kit. At 36V it will climb hills faster than any motor Crystalyte makes. There are two Model of X-5. The Model 504 and Model 505. At 36V the 505 will reach a speed of 20 mph in a 26" wheel for on road and the 504 will reach a speed of 30 mph for off road use As a rear motor it can come with up to a 7 speed Freewheel.

So, there it is. I am hoping that someone out there can help me figure out which motor/ battery pack configuration would be best efficiency, power and run time.
Thanks,
Arnold