About copper wire and Neodymium magnets
First figure out how many winds your application needs/wants. Then, for that number of winds, use the thickest wire possible, or wind 2-3 in parallel. Fill up the slots completely with copper, to the rim, to the rafters . This will give less resistance and thus a better efficiency. A higher efficiency means that you can put more power through your motor before reaching too high a temperature. Specific power (power/weigth) increasesOf course, more copper means slightly more weight, in some applications there has to be a trade-off between efficiency and weight.
About Neodymium magnets
Use the stronger Neodymium magnets (N45, www.supermagnete.ch has N50!). For a given number of winds, torque will increase and rpm will decrease. Now we'll do it the other way round. Say you have a ferrite motor with the Kv you want. Great. Now replace the ferrite magnets with neo magnets, Kv goes down and Kt goes up. Bummer, wrong Kv, say only 50% of the original 100%. To get Kv up again, you can rewind the motor with less winds, 50% of the original number of winds. Super, Kv is back on the track again and resistance is down by 50%. Since there are now less winds there's room for thicker wire, or winding in parallel, again resistance goes down by 50%. Net result with Neodymium magnets: same Kv and a quarter of the original resistance. This is the great advantage of Neodymium magnets, a higher efficiency.
The motor is therefore able to handle more power. A motor with an efficiency of 80% can handle e.g. 200Watt. 40Watt is converted into heat/temperature. The 'same' motor with an efficiency of 90% can handle 400watt and burn 40Watt at the same time.