Use of "here" in the middle or at the end of the sentence

It's a matter of style. In paragraph 18 of The Elements of Style, Strunk and White advise: "Place the emphatic words of a sentence at the end."

In the case of the chair, the important word is "chair"; we know the object is here, but we don't know what the object is until we are told. If the chair were thought to be missing, then we would say, "No, the chair is here." But since the purpose is to say what object is here, we put the important word - chair - at the end.

Likewise, if I want to tell you where to look for more information, I say, find that information here (with a link). If I want to tell you how long they have lived here, I say "They have lived here most of their lives." If I want to tell you where they have lived most of their lives, I say "They have lived most of their lives here [often with a further identifier]."

The object here is the chair. The object is the chair here.

They mean two different things (well, actually three).

In the first case you're either saying that the object of this discussion is the chair, or you're pointing to an "object" (which may just be a X on a drawing) and informing your listener that that is the chair.

In the second case you are saying that the "object" (of discussion?) is that particular chair (the one that's "here").