It opens with just a light touch. It seems that the rubber part is particularly short, and there is not enough friction to keep the cover tightly closed.
Yep. I got mine yesterday and the cover is barely on there. I suspect the USB C port itself is water resistant like those on cell phones, but I wouldn't want debris or water getting in there regularly…
It is a bit loose, but with the silicone case around mine, it’s a bit of a non-issue. You still have to “dig” out the door to open it.
According to DC Rainmaker, "The port has a little cover, but it’s also internally waterproofed to IPX7. "