He says there's prompts for gates that are locked, and particular keys work for the sections they're labelled for. There was a conversation about being given one, or finding another. I can't remember, I'll have to check.
The numbers would actually also correspond with train lines for the station, and which exit number it is. So it could be referencing platform 2, exit B, platform 5, exit D and so-on. It is absolutely a train station. Someone on the FFXV sub took a lot of photos of signs in Insomnia, so here is one to show you what I mean:
The underground probably connects up with the shutters/gates, which would make sense I guess.
And going from the other photos in the same topic, I would assume so about the Esterway. Where they started the stream earlier had a lot of space, so we could but I don't really think so. OG said something about in Comrades needing to go to Hammerhead via shuttle to do the quests for the bros, but he's not said anything much about other areas aside from Insomnia and noting conversations, quests and other things.
So I really don't know about going out in WoR as he's not said anything about that.
OG said he's noticed three or so things with Ifrit, as well as a Comrades sort of event or dialogue prompt if you trigger a game over during that from Ardyn. However, he also said the original version, including Shiva's original dialogue before the last update is still in the data too, so he said that with knowing the change from the previous update, he thinks it's best to wait and confirm as he doesn't want to jump to conclusions.
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The Luna parts he saw were split up, one was before the Kings bit, and another thing was kind of mashed in-between things. He said that where it is floating around doesn't really mean much on that sort of thing, so it's pointless to ask as the event IDs are already in numerical order.