I don't recall if it came in the fuselage or finishing kit, but I agree with Carl that magnetic microswitch set for each door came in one of the kits. I wired them into my G3X system, rather than using the relays and warning lights that came with the kit.
I wired mine in fail-safe mode (e.g. open circuit = door open). Just requires selecting the right input and configuring it to alarm on low.
Correct. Wire all four micro switches in series. A green light then means all four door pins are engaged.
Carl