It's good stuff, basically really really smooth and creamy autobody filler. It's nice in that, since you have to mix it, you don't have to wait a long time before you can get back to work, and there's no guessing about when it's going to be hard like with the non-mixed putties.
No, it just uses a small amount of hardener like regular autobody filler. In fact I'm pretty sure the hardener is the same, as when I worked at a body shop there was just one giant tube of hardener for everything.
It gets plastic-hard like regular body filler, though I would say it's not as strong so I wouldn't use it for gluing or casting whole parts, though it does flow well enough to do so if you wanted.
