If I add CCTV's through this plugin with the mainstall CargoShipCCTV and mainstall TrainStationCCTV commands, how do I get the codes for those camers?

You can see the CCTV ids multiple ways. In the profile data file, or using the mashow command (a bit awkward for a moving cargo ship though), or you can mount a static computer station nearby to see what they are (they auto register). Those profiles already include computer stations, so you can mount them to see the ids.

Note that there's a numeric suffix for the actual name seen in the computer station, which you won't see in the data file for example, because it depends on how many of the monument are present.