No (at least, not a Nikon teleconverter) and no. Teleconverters are really designed for use with big prime lenses.
I'm thinking of going for the 80-400vr lens this year. Might sell my 70-300 (non vr) to help finance my new lens!
Not a bad idea. However, beware of the foibles of the 80-400, namely slow AF.
A 300 f4 prime is worth considering instead. No zoom obviously, but mugh higher quality.
Thanks for advice Joe.
I've got a feeling that the 300 f4 might be beyond my budget!