3D Shot is an instant "photo" of a Second Life object. It is a link viewable in any browser, no Second Life required.
The primary goal is to allow showing your creations without Second Life: at SL Marketplace, in blogs and Facebook posts. It is like a live picture which you can enter, rotate and zoom.
No, 3D Shot is not connected with an original object. Original object can be modified or removed, and 3D Shot survives.
Yes, you can do a shot of any object, even if you don't own it.
3D Shot it is not a tool for "copy-catting" an object: the copy is rougher; it does not contain important building data and scripts; all the data used is equal to a regular viewer's usage. The texture quality is much lower, too.
No, only SpeedLight viewer 3D allows creating 3D shots.
Yes, we plan adding 3D shots of avatars, too. This is a bit more complex task because of animations and such. But we plan to implement it as well.