Yes and yes. Also, Guru is the one that gets all the boards and eventually dumps them (gets boards from collectors, buys the boards himself etc). Since the ZiNc people (DynaChicken, smf, R. Belmont) also work with MAME, and have done so for a long time, they have some hardcore knowledge of arcade hardware. As for how they get their data... Guru's dumps, analysing, debugging, reverse engineering, leaked technical documents, you name it.