DCC voltage is of equal amplitude in the plus and minus direction an made up of a series of pulses Which provides the information as to which device is being controlled as well as providing the power to operate it. There isn't a measurable DC type voltage that you may be used to. Conventional 12V DC accessories will not work off track voltage
For all two rail locomotives that would usually come with a DC motor, yes... The DCC signal follows the same pattern as the AC wave, but it is still a DC current in two rail applications...Is the motor in an DCC engine D/C?