Vivitar 70-200 macro?
Are you sure? I have one 70-200/4-5.6 macro (1:4) in Nikon AIS and it's a pretty decent lens. Doen;t flare up too much, color rendition is accurate and there is no light fallout.
I'll double check any other details on it since I don;t have it with me.
Most vivitars were good, and the Series 1 were outstanding lenses for the time. Vivitar never caught with AF.
Now your questions:
--does this sort of lens configuration make sense as an add-on to this camera--add telescopic plus close-up capability to the standard lens.
70-200 is a very handy zoom lens to have, from small tele to tele. The close-up capability is something that maybe useful to you.
--are nikon lenses significantly better than the competition?
In most cases yes. But Vivitar "consumer" zooms are of comparable quality. The Nikons had better coatings IIRC.
Othe rband to consider IMHO is Tokina, excellent quality both optical and construction wise.
--where would I go looking for an equivalent nikon lens, if I decided on finding one?