Headscratchers / Banshee Chapter

• So, those who take DMT begin to hear number station sounds, that is understood. But how come these sounds are present in a video left by James and his friend? Isn't this supposed to be a thing that only they could hear and no one else? So far it seems to be just a weird mistake of the scenario.
• It is unclear why Thomas and Callie remain in safety for a very long time despite having been taking the drug from time to time, probably for months - none of entities comes for them before the very last night spent with Anne. In addition to this Thomas is shown to have been a test subject, so he had already been exposed to this stuff a long time ago, many years passed. In contrast to Thomas and Callie, James and Renny are assaulted instantly as soon as James takes the drug.