The nRF52832 ships with an empty flash, so there is no firmware on it from the factory. You can read out the flash using a debugger, such as a SEGGER J-Link variant. Assuming you have a SEGGER debugger (stand alone or using a nRF52 DK), you can use "nrfjprog --readcode".
(If you want to develop for the nRF52832, then you should look at the nRF5 SDK).
Yes, it has an optional Access port protection (often called "read-back protection") mechanism. If enabled, the only way to disable it is to do a full chip erase, so that an attacker won't access any data from the flash.
