@Lanefan,
@doctorbadwolf, and others have said all the things that really needed saying to debunk this list of thou shalt nots. Yet I still find my fingers drawn irresistibly toward the keyboard...
1. Long Monologues/narrative descriptions/cut scenes;
I'm okay having all of these in the game. Hell, I've been doing cut scenes in my home games since the early 90s. And monologues and narrative descriptions go back to the beginning of gaming. How long is too long for a bit of scene setting description? Depends on your table.
2. Focus too much on NPC talks;
Talking to NPCs or NPCs talking amongst themselves? If NPCs are talking amongst themselves, presumably the GM is doing it because it's providing some useful drama/info. Okay, yes, it's a big world, there's bound to be GMs out there who are doing it solely for their own amusement and that would be subpar, but how often does it really happen? As for PCs talking to NPCs... for some players that's 100% of the game. For most players it's a greater than 0% of the game.
3. Wait for the "perfect" moment to introduce a new/replacement PC;
Okay, this one I can be onboard with. But it depends on your game.
If you're just having a classic beer and pretzels monster bash don't wait, just have the new PC appear. There's wandering monsters, why not wandering PCs?
For myself I prefer games with a consistent narrative. So by preference I will wait for a good spot to bring in new PCs. In the meantime the player can run NPCs or even help me run the bad guys. Of course my preference isn't always going to work. In the
Reign of Winter AP I had to introduce 2 new PCs inside Baba Yaga's super secret personal demi plane that no one in the universe knew about. I just had them show up through a planar gate, the last survivors of another adventuring party that had been working to stop the BBEG's plot. Did this undermine some of the pre-existing narrative? Yep. Did anyone care? Nope.
4. Plan for Three hour long fights;
Eh, long fights is part of the game. As others said above, most of what makes a fight drag is time wasted by players who can't/won't focus, and/or have no idea what they can do. And of course many players love a big fight scene.
5. Putting the story before the game;
Railroading? Yeah, that's bad. But there are times the story is the game. It depends.
6. Have temporary characters that are planned to be killed off;
No problem with this at all, as long as the player wants to of course.
7. Allowing PVP or truly high tension Player moments;
Depends on the table, but a lot of good fun drama can be milked from this. Some players love it, some hate it. Some game systems (GURPS, Hero) really do lend themselves to arena combats where the players can test their builds against one another.
8. Letting characters talk endlessly;
Ummmmm, if the players are happy, why interfere? Let 'em talk.
9. Setting expectations too high.
Well, by definition too high is, you know, too high. No-one is going to do this deliberately.* Yeah too high expectations will happen sometimes, learning how to set realistic expectations is a life skill we all learn with time.
So is this a list of things not to do? No. It's a list of things one should approach in a considerate manner. Everything on the list depends very much on the table.
*I know, it's a big world, someone has.