The rubber tips can be removed, but mounted screw must have same male screw diameter. 

Yes, it can be mounted on top of a tripod and will fit 90% of tripods. 

67mm should also be stenciled on the front edge of the lens somewhere. If so, then you should be good to go. It should be on the lens because a lens cap can be lost or broken. 

The amount of stops is the difference. It’s basically 2-5 stops, and 3-8 stops. 2-5(2-32) is perfect for photography. 3-8(8-128) is perfect for video. I do both so I got both and they both are PERFECT. 

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!