English isn't galaxy76 strong suit but here are some tips if you can understand:
Max voltage: Possible to use 6s but not recommended for longevity of motor. 4s-5s is acceptable.
Max temperature: No more than 70C after 15 minute run
Max RPM: If you are worrying about this then you have other issues in your vehicle.
Gearing: Gear ratio will be DIFFERENT DEPENDING ON YOUR APPLICATION. This link will allow you to calculate top speed
http://www.scriptasylum.com/rc_speed/_top_speed.html
For E-maxx I suggest start with max speed of 30mph. If MOTOR, ESC or BATTERY gets too hot then reduce top speed by changing gear ratio.