Yes, it will fit any Sony e mount body, either full frame (a7..., a9...), or aps-c (like a6500, etc) 

hello Nikon 18-55mm f/3.5-5.6G lens size is 55mm, so the filter can fit it 

For camera with telephoto zoom lens, you need to buy a tripod mount ring additionally or telephoto lens bracket for better balance) 

yes, i had no problems with infinity focus with this adapter. the only FD mount lens i use anymore with my sony is a vivitar 20mm, and i pretty much only shoot infinity focus with it. 

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!