I have seen laminated, wood-'looking' flooring that was glued down, just like asbestos or real-linoleum tiles, but it's been years. Most engeineered floor products I'm aware of 'float', generally as you describe....at least the brands I've installed (Ikea and Armstrong). I've never had anyone kick it or slip on it and have it come apart, and particularly with stuff on it, it doesn't move at all (at least not visibily).

And yes, the stuff I've used required a gap around it. The installation kit I got came with little 'wedges' to help/ensure that.

"Engineered Flooring" is a sandwich of 1/16" to 1/8" inch of finish wood on top of a plywood base with a total thickness of 3/8" , 1/2" or 5/8". These floors can be nailed, glued or they can float depending on the manufacturers T&G detailing and the thickness of the flooring.