So what would happen if an animal used the Animal Key?
They turn human. That's how Bode could come back to life despite his body being cremated.
How come the whole "Dodge looks like a corpse in mirrors" thing never came up again?
He used the wellhouse key. Seems like that turns an echo into a real human being.
The Echo Key only brought him back - the entire plot of Welcome to Lovecraft explains that Dodge can't actually leave the wellhouse, and requires the Anywhere Key to escape, which is why he eventually steals it from Kinsey's bracelet to finally escape.
If Dodge goes through the wellhouse door in his current post-Clockworks form, will the soul of Dodge and the parasite be destroyed and leave an empty body, or will nothing happen?
The former. Rufus manages to snag Dodge!Bode once the latter's plan turns to shit, and forces him through the Wellhouse door. It evicts Dodge but leaves Bode empty.
If Rendall Locke wanted to get rid of the Omega key, why not just melt it down?
How is is Tyler locke able to make a key that does exactly what is needed? I mean, for that matter, how are any of the keys made with a specific purpose in mind? Can you just make a key that does anything?
Why is the giant key giant and wooden? Firstly, the keys only work due to demon metal so the wood is entirely stylistic. Secondly, it would be way more convenient if it was normally sized.
If no adults can understand the keys, how does Mrs. Locke immediately figure out how to use the fixing cupboard/key?
I get that magic is supposed to help, but with the number of high school students and other people who died in that last story, how could anything go back to normal? I mean, a federal officer among many, many others dies under odd circumstances and more than one student dies with odd metal leaking from their orifices. It's all well and good that the children forget what happened as they get older, but that doesn't stop it from having happened. For that matter, after the original 1980s tragedy, it's hard to believe more didn't come of it (at the very least the cave seems like it would have been dynamited shut).