Tokens do not have a mana cost unless the effect creating them assigns a mana cost (such as by making it a copy of an object with a mana cost). Any object without a mana cost (including lands and cards like Asmoranomardicadaistinaculdacar) has a mana value of 0. You'll notice Culling Ritual doesn't say anything about the mana cost of permanents, rather the mana value. A mana cost of is different from not having a mana cost, but both give a mana value of 0. Just like a mana cost of is different from a mana cost of , but both would give a mana value of 1. This is also why Culling Ritual specifies nonland, because otherwise it would destroy lands despite not having a mana cost, because the mana value is 0.

202.3a The mana value of an object with no mana cost is 0, unless that object is the back face of a transforming double-faced permanent or is a melded permanent.

Regarding nothing not being a mana cost, that is correct. Memnite shares a mana cost with Ornithopter, but Dryad Arbor does not share a mana cost with Asmoranomardicadaistinaculdacar since neither of them have one. I think the only cards that care about this difference are Killer Cosplay and Richard Garfield, Ph.D., neither of which are black boarder legal.

The two previous keywords that made token copies (Embalm and Eternalize) had special rules to remove the mana cost from the token, you can see it spelled out in rules text on Vizier of Many Faces as it's clone effect would normally strip the Embalm changes if they weren't included. This was likely done because of the understanding that "tokens don't have mana cost" as a rule, despite exceptions (such as Cackling Counterpart) already existing at the time. Wizards changed their approach with the Offspring mechanic allowing it to maintain mana cost. This change may have been related to Modern Horizons III introducing the ability to make tokens of cards (such as Ral and the Implicit Maze) which already have costs, but also could have been because the ability to create copies of Permanent Spells (which resolve as tokens with mana cost) was added to the game since the previous keywords were made.

Changing control of a curse with something like Donate will not change who it's attached to, only who controls it. With most curses, control doesn't really matter (some like Curse of Misfortunes or Curse of Leeches  ^Flip do care who controls them). In order to change what an aura is attached to, the spell would need to state that like Aura Graft does, however the only thing I can find to do that would be Ardenn, Intrepid Archaeologist which requires you to still control the curse, and is not available within Lynde, Cheerful Tormentor's color identity.

Gahrzerkire The permanents enter one at a time. This is different from something like Genesis Wave. Permanents revealed (and therefore entering) later will not see the ones that entered earlier, so something like Soul Warden will only trigger off later permanents, not earlier ones. That said, all of the triggers will be added to the stack only after Primal Surge finishes resolving, and may be added in any order, so you can resolve the first one that entered before resolving any others, or after resolving all the others. You'll notice that was included in my initial answer: "That said, all the triggers go on the stack at the same time, so you are of course able to order the stack as you choose." You are correct that they will need to wait for Primal Surge to fully resolve before any trigger is put on the stack.

Field of the Dead will only trigger once there are 7 or more differently named lands, so if you cast Primal Surge while only controlling Forests, you'll miss a bunch of triggers. Again, this is different from something like Scapeshift where all of the lands enter simultaneously.

The important thing to notice is that Primal Surge directs you to put the card onto the battlefield then repeat the process, instead of having you put all of the cards onto the battlefield after you've finished the process. Spells can contain multiple steps that will trigger abilities at different times. When this happens, the triggers wait to be put on the stack until after the spell has fully resolved, but resolving the spell still takes those multiple steps sequentially. Another example of this would be something like Austere Command where you destroy different sets of objects twice. If you destroy enchantments and creatures mana value 3 or less, Fecundity would not trigger while Femeref Enchantress would trigger, because the steps do happen sequentially. You would still need to wait for Austere Command to finish resolving before Indebted Spirit's trigger is put on the stack, so the token it creates would not be swept up in the second mode.

I do believe the ruling is wrong, but it's not entirely clear. The reason Mindlink Mech is different from the other examples is that the copy it becomes is not a creature. Anikthea, Hand of Erebos can set the power and toughness of the copy because it explicitly states that the copy is a creature. Mindlink Mech only states that it's a Vehicle artifact in addition to it's other types. So when it becomes a copy of Mishra's Factory the copy effect makes it an Artifact Land - Vehicle. The reason it's still a creature is that it is still crewed, and if you somehow turn a Mishra's Factory into a creature using a crew ability it will in fact be a 0/0. The issue is, this should also apply to if it becomes a copy of a vehicle, because vehicles can't have power/toughness unless they're crewed, exactly like every other non-creature permanent, so there isn't really a reason to treat them differently in this case.

208.3. A noncreature permanent has no power or toughness, even if it's a card with a power and toughness printed on it (such as a Vehicle). A noncreature object not on the battlefield has power or toughness only if it has a power and toughness printed on it.

The reason to say a vehicle would still be a 4/3 is the next subrule, but it should apply to any permanent (including a land). The reason it might not apply would be that it's discussing power/toughness setting effects (Layer 7) rather than copy effects (Layer 1), but as it doesn't explicitly say such, I believe it would still apply and make the Artifact Land a 4/3.

208.3a If an effect would be created that sets the base power and/or toughness of a noncreature permanent, or otherwise modifies its power and/or toughness, that effect is created even though it doesn’t do anything unless that permanent becomes a creature.