Holding, Delaying, or Readying an Action? – Rules As Written [duplicate]

Please point or link me to any official rules (rules as written) on when a character can delay, hold or ready an action for later in a round, instead of going on their initiative.

What does a character have to do to delay or hold an action during a round?

What actions are characters allowed to take when they delay?

Is my accidental house rules on weapon damage in D&D 5e balaced?

TLDR: In my game, finesse and ranged weapons don’t get a stat damage bonus and Dueling gives the damage bonus to 1- and 2- handed weapons. Is this balanced?

Starting running a game for the first time in several years. Two of the players are new to D&D (a Warlock and a Bard). The other hasn’t played since 2nd edition (a Ranger).

During character creation, I gave them incorrect rules about weapon damage which I must have misremembered. I told them that Finesse and Ranged weapons don’t get a damage bonus, whereas other weapons get a strength bonus. The correct rule, having checked, is that Finesse and Ranged weapons get a damage bonus from dexterity.

Now, the Ranger player, remembering 2nd edition, gave his character a high dexterity for archery, but chose to have them wield a longsword with no shield. That means has base damage dice is the same as the bard with his rapier – both a d8. However, his bonuses are actually lower. At 1st level, he was a worse fighter than the bard!

After the first session, I took his player over the bonus and dual-weapon rules and checked if he wanted to keep using the longsword and not use a shield, and he did: he just chose to wield it two-handed for the higher damage dice. So I decided to keep my rules error a feature of the game. That way at least the Ranger gets a bonus on his damage dice, and the Bard does not.

I’m not sure why the Ranger wants to keep the longsword, I think he’s just got a strong image in his head from his 2nd edition Ranger characters. As a result, I also rejected the obvious compromise of letting the Ranger have a "longsword" that’s actually a rapier. I figured that might also cause problems with distributing magic items (is it a rapier? is it a sword?).

At 2nd level, the Ranger chose Duelling and, again, I’ve let him keep it as +2 damage with his longsword even though, strictly speaking, it’s not supposed to be used two-handed.

I haven’t explained to the players that I’ve got the rule wrong. Not out of fear of losing face but because it makes the party a little better balanced, and I don’t want the Bard claiming his +3 damage, putting him back in front of the Ranger. None of the other players has a rulebook.

I don’t believe this is in any way game breaking: it just gives the party a marginally lower damage output. So long as I tailor the encounters accordingly, I don’t see it as an issue. But I know D&D 5e is much better "mechanically balanced" that some older editions and I might have missed something. Is my approach here balanced and fair?

Are there any 5th edition elemental plane rules or details?

I have been reading through Volos Guide to Monsters and Mordenkainen’s Tome of Foes and gained a lot of interesting knowledge of various facets of the D&D universe, namely the 9 hells, abyss, feywild, etc. Even the Astral Plane is covered in both the Mind Flayer and Gith sections of those books.

However one area that I have not yet found any detailed information on are the elemental planes.

Has this information been published in a D&D 5th edition book yet, or is it something we are waiting on? I am specifically looking for details on the various details of each of the elemental planes, ideas for running adventures in each, the population centres and what they consist of (for instance I know historically there is a city in the Fire Plane), the native inhabitants and how they exist and live in each plane.

I know there are brief descriptions given in the PHB and DMG. I am looking for anything of more detail that may have been published in 5th edition. Or, failing that, suggestions of previous editions sourcebooks I can mine for information.

Is there a summary of Nobilis 3rd edition rules for new players?

I want to start a game of Nobilis, but the 3rd edition book is huge (more than 300 pages) and I clearly can’t ask my players to read it, even only the rules chapters.

I found What are the basics of the Nobilis 2e system's mechanics, in a nutshell? but it is only about the 2nd edition. Having read both I feel like the 3rd edition rules are quite better (even if the 2nd book is a wondrous object).

Is there any good summary of Nobilis 3rd edition rules for new players?

Are the Revenant rules official? If so which book are they in? [duplicate]

Critical Role spoiler ahead:

I have found the rules for this listed on Unearthed Arcana and homebrew sites but have the rules for Revenants been officially published as of yet? and What are the playable D&D races in 5e, and where can I find them?. lists as below:

Revenant (UA: "Gothic Heroes"), actually a subrace that can be applied to human, dragonborn, or tiefling

Does this, therefore, mean that Revenants are not official (come under the unofficial/official that UA rules do until they are published officially in a paid for book)

Sleepless PCs and Exhaustion Rules

The rules specifically speak about the need to sleep. If a PC or any character for whatever reason does not sleep, by RAW, why would this rule effect them?

Xanathar’s Guide to Everything gives the optional rule for "Going without a Long Rest"

Going without a Long Rest.
A long rest is never mandatory, but going without sleep does have its consequences. If you want to account for the effects of sleep deprivation on characters and creatures, use these rules.
Whenever you end a 24-hour period without finishing a long rest, you must succeed on a DC 10 Constitution saving throw or suffer one level of exhaustion.
It becomes harder to fight off exhaustion if you stay awake for multiple days. After the first 24 hours, the DC increases by 5 for each consecutive 24-hour period without a long rest. The DC resets to 10 when you finish a long rest.

And the PHB specifies a Long Rest as:

Long Rest
A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps for at least 6 hours and performs no more than 2 hours of light activity, such as reading, talking, eating, or standing watch. If the rest is interrupted by a period of strenuous activity-at least 1 hour of walking, fighting, casting spells, or similar adventuring activity-the characters must begin the rest again to gain any benefit from it. At the end of a long rest, a character regains all lost hit points. The character also regains spent Hit Dice, up to a number of dice equal to half of the character’s total number of them (minimum of one die). For example, if a character has eight Hit Dice, he or she can regain four spent Hit Dice upon finishing a long rest. A character can’t benefit from more than one long rest in a 24-hour period, and a character must have at least 1 hit point at the start of the rest to gain its benefits.

If a character des not need to sleep, do these rules effect them?

I understand that sleep is not rest. However, both of these rules specifically state sleeping is a requirement. The question was not is sleep the same as rest.

How does rule 3. Advantage and Disadvantage from Ten Rules to Remeber function?

Ten Rules to Remember in Tasha’s Cauldron of Everything reminds us via rule 3. Advantage and Disadvantage:

Even if more than one factor gives you advantage or disadvantage on a roll, you have it only once, and if you have advantage and disadvantage on the same roll, they cancel each other.

Now that leads to the natural question of in what order these things happen. When you gain "advantage" from multiple sources and "disadvantage" from one source, do you only gain "advantage" once that then is cancelled out by "disadvantage" thus resulting in neither or do you get "advantage" once from one source, that then is cancelled out by "disadvantage" from one other source thus allowing for "advantage" from another source to take place – as there are neither "advantage" nor "disadvantage", at that point, in the chain?