Harlington already knew Jimmy's identity. An FBI senior agent is quite different compared to the private detective he had previously hired, and Jimmy is also Kevin's son-in-law, a member of his own family's younger generation.
Since Jimmy said to wait in the bedroom, then just wait. He's one of us, no need to worry about what he might do.
Jimmy walked around the room once, then opened the door and went outside. The light at the door didn't matter to Jimmy; he had already determined the general location, and now he needed to figure out what was specifically causing it.
The sound in Jimmy's ear wasn't loud; for him, it was essentially like a little more static when watching TV. Although it affected his hearing, it didn't have much impact on his mind.
