It does not. Currently, all it does is replace the "PS Remote Play" app you can put on your phone, which is basically just remote desktop for your PS5. Without a PS5, all you have with the Portal is a screen that doesn't do anything.
This update will allow it to stream games from Sony's servers, instead of from your own PS5. But it is still limited just to Sony's platform.
Pepe was previously coopted by far-right groups. The usage has died down since the creator of the original comic began suing people, but there are still people who put Pepe in Trump hats and shit.
Warframe is a bit similar to Destiny in that it's built around multiplayer, but most of the main content can be solo'd if you wanted. But that said, the Warframe community is still thriving, so it should be pretty easy to find a group to play with if you want to avoid the in-game matchmaking.
They're usually put in the game's credits. The promotional material is part of the game even if it isn't on the disc, it isn't some separate project that exists in a vacuum.
The author says "think about it", but clearly he didn't.
I wonder if it's a licensing thing. I know a few of these games had heavy use of licensed music, like Jet Set Radio and Crazy Taxy. At least, the original versions did, I'm not sure if that's the case for the Steam ports.
Probably a pessimistic take, but I don't expect this to have any discernable impact on sales, or any other effects that would discourage publishers from these practices. The average user doesn't care about or understand how these things work; they'll see an anti-cheat warning on the store page and think "Okay, tell the colonel I'll be on my best behavior then" and continue to buy the game.