Yes I got this sorta by mistake. I am so glad. It is thick and clear. I taped it to my really old windows in the back of my home. And to seal across my skylight in the bathroom. It's working amazingly. For years I was using clear drop cloth plastic. Never again.
Yes nearly crystal clear.
This is a 4 mil thick vinyl sheeting.
if applying outside, heavy duty duct tape. if applying inside use double face tape around the window frame, apply film and then trim.
No, this is not a replacement for a car window.
We do not do a flame spread test on this product since it is used for either making window insulation kits or for covering items