I can only speak for my Nikon 50mm f1.8 Ai-s manual focus lens and the Olympus Pen-E PL7. The K&F Concept® Nikon - M4/3 lens mount adapter ring for Nikon AI lens is well suited for this. The adapter sits firmly and without play on the lens and can be easily attached to the m4/3 bayonet. 

That depends on the lens diameter. This is usually indicated on the lens. The filter holder is then attached to the lens with the appropriate adapter ring 

Nope, there is no electronic communication with your panasonic camera and nikon lens 

This adapter fits the Panasonic G85 perfectly. If your lens is a Nikon G lens, then you should have no problems. The version of this adapter I have is M43 (Micro 4/3rd) to M42 lens. Hope this helps. 

The adapter will mount the lens and you will be able to use it manually. However, my copy of the adapter does not allow the lens to be fully mounted all the way until it clicks into place. It doesn't quite make it, but it's still very solidly mounted. Also, the manual aperture linkage doesn't work properly (on my copy, at least) so exposure is controlled only by shutter speed and/or ISO. You will be able to manually focus and zoom the lens but no VR, of course. It will be a frustrating experience. Instead, get a 14-140 Panasonic zoom if you can afford it!