I cannot answer your question. In AZ/USA, we do not get many freezes, so I have never had a chance to try it out in colder weather.
The other part is fairly easy. The opening of the trunk, remotely, is managed by a switch on the driver's door, or by depressing a button on the exposed underside of the trunk lid. The auto-closure button is not accessible, when the trunk lid is closed - only when it is open. As another poster noted, you need to learn to keep your nose out of the locus of the trunk lid, as it closes. The trunk lid is brought down to near closure, and then it "snuggles" down to a "latched" position. This similar to the door on the S, in that they only need to be partially closed, and they will latch themselves. Unfortunately, I have gotten a bit lazy and find that I do not completely close the door on my Landcruiser. Note: it does NOT have the auto-latch feature, and I must then open, and re-close to secure them.
Hunt