Answer: There is a front thread that allows another filter to be mounted to it, as long as it has the same aperture 

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

Yes, it has one 

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

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!