1. While I sort of agree with this, there neads to be a plot, I have to say that suggesting you use stories like LotR or Beowulf is a terrible idea. This leads to railroading as your players have no agency to alter the story. By all means have a lead where the McGuffin needs to be destroyed at the PlaceOfTerror, but have a backup for when the players refuse that lead, or don't pick up on clues that the PlaceOfTerror is that way.
2. Critical failures can be funny. Most of what I have to say about this is to other commentors in this thread namely:
Critical effects should be balanced against each other. If there's a critical hit, there should be a critical miss...
Sorry Shiroiken, I just found your post first.
I disagree with the premise. Critical effects should be balanced across the sub-systems of the game. As an example I am playing a wizard through Out of the Abyss - 25 sessions in and my wizard has make exactly one attack roll. So across all the sessions so far he's had 5% chance to critically fail. Compare that to the martial characters who make dozens of attacks each round. If you have critical fails that have a mechanical effect then it needs to affect combat, magic, skill, etc
Critical fails can be funny but they need to be in line with the rest of the game. I don't think that belongs in 5e because 5e gives with both hands (compared to 3.x where you got +2 in this and -2 in that). Critical hits in 5e have a very limited effect after level 3
6. This is true as a player as well. For reasons I am keep the diary for our group, and I post them on a larger gaming forum. My DM has mentioned several times how useful that is in keeping his timeline in line with ours. In short, if you play D&D write stuff down.
7. Again, Ipartially agree here. Something like initiative is not worth pre-rolling - especially if you usually roll in the open. You can do this at the same time as the players. But you can have stuff like random encounters pre-rolled to avoid a big pause in the action.
8. On top of that - unless you are playing with (and aren't yourself) a total newbie to the game - get the players to look stuff up, while you move the game on with another player. While you are looking through the rules the players have nothing to do. Similarly don't be scared if making a ruling and a note to look it up later and address anything in the next session. Unless it is truly game altering (like a player death) its not worth pausing the game for.
9. Falls under the same points I made for 6