When I connect 2 motors to a battery do the motors share volts or amps?
First the mAh stands for the charge-capacity of the battery. Which means your battery can provide a current of 3 A for an hour (theoretical-In real it is less) or 1 A for 3 hours and so on (3000 mAh = x A * y h). This will not be influenced by your curcuit.

The voltage over each motor will be different dependend on how you wire them. If you have them parallel to each other the voltage will be 8.4 V over each motor.
If you have them in row and they are from the same type with the same resistance the voltage will be 4.2 V on each motor.

The current that will be flowing depends also on the wiring you have. If they are parallel to each other every motor needs its "own current", so you have twice as much as single motor. If they are in row they use the "same current".

For further informations try to look up "Kirchhoff's Curcuit Laws" (Wiki). They will help you to understand these circumstances.