Why is the left side of a boat called "the port" and the right side "the starboard," and the windows all around the boat "portholes?"

First let's define "Port" and "Starboard":

Port and starboard are nautical terms for left and right, respectively. Port is the left-hand side of or direction from a vessel, facing forward. Starboard is the right-hand side, facing forward. Since port and starboard never change, they are unambiguous references that are not relative to the observer.

https://en.wikipedia.org/wiki/Port_and_starboard

"Starboard" is from the Old English "stéorbord", where "stéor" means steering-paddle or rudder. According to the OED, " The etymological sense of the word refers to the mode of steering the early Teutonic ships, by means of a paddle worked over the right side of the vessel."

Since the paddle was on the right, the dock had to be on the left.

Since the steering oar was on the right side of the boat, it would tie up at wharf on the other side. Hence the left side was called port.

https://en.wikipedia.org/wiki/Port_and_starboard

"Port" in "porthole" is the French "porte" or Latin "porta", meaning a gate or door.

The original name for the left side of the ship was not “port”, but rather the Old English “bæcbord”. This was probably referencing the fact that on larger boats the helmsman would often have to hold the steering oar with both hands, so his back would be to the left side of the ship.

http://www.todayifoundout.com/index.php/2013/01/the-origin-of-port-and-starboard/

In the old days ships would tie up to a dock with it on their left side. Therefore the Port of call was on the leftside. Before rudders, a "stearboard" was on the aft right side of the vessel, hence the term Starboard. The hatches on the portholes were closed at sea, but open while in port.

So why did "port" used to be "larboard"?

My OED infers that "port" comes from the side of the ship that would have been nearest the harbour wall - presumably to stop damaging the steering paddle. And isn't the "proper" name for a porthole a scuttle?