If a modded starting system was not used the player's starting science ship will always be 0. If a modded starting system was not used the player's empire will always be 0.
If a modded starting system was not used the player's starting leaders will always be 0 (ruler), 1 (governor) and 2-5 (scientists). Leader IDs can be read by hovering over a leader in the leaders or empire menus.If a modded starting system was not used the player's species will always be 0 for the main species and 1 for the syncretic/cyborg/bio-trophy/prepatent species. Species IDs can be read by hovering over a species in the species menu.Species, leader, empire and pop IDs however are defined when the game is created and have to be found with the debugtooltip command.
Most IDs are predefined and can be found on the ID page.