I mean, if the FBI drops by for a chat, encouraging them to stick to the living room is probably not unusual. But if you're being asked for a document present in your house that's going to take 10+ minutes to find, inviting the agents along or bringing the relevant folders/computer/whatever to where they are sounds pretty reasonable.

Not necessary, which is obvious from the agents agreeing to this request. But maybe a good way to forestall concerns like "what if they think I'm forging the document right now?"

I think the assumption is if they are "at your door" they probably know you don't have it.