The only question not answered. The only question worth answering.

Worst case scenario, voltage detectors (or your fingers) don't lie. Turn on the power, check the wires, see what's energized when the switch is off.

I was referring to the linked article, not OP's picture. As I assumed you were doing, too, when you said, "Not those colors".

Sounds pretty normal. For a single pole switch, line and load are interchangeable. Without a neutral in the box (actually I lied - there is a neutral in the box, but you can just ignore it; tuck it deep in the back of the box), there's nothing to confuse or do wrong. Ground to ground. One of the black lines to one of the gold-colored posts, the other black line to the other post (you'll want a pigtail for the line that is two twisted-together black wires). Differentiating line vs load only matters if you're using a smart switch or 3-way switch (two switches control one light).

Looks like a shittily wired box. Either there's a line and neutral with no load (in which case, you would wire a receptacle there, not a switch), or it's an old school no-neutral lights-only loop and they used white for load. Both are wrong, but given they're wiring a switch one would have to assume it's the latter and would still work even with the colors being wrong.

Switching line and neutral would be pretty stupid.

You're overestimating what a level 2 charger needs. 30A is more than enough to overnight charge anything less than a Hummer EV. Adding more is unnecessary and a little silly, but I wouldn't say it's necessarily unsafe.