This is one of my most favorite subjects, lets put on our tinfoil hats peoples and dig in :)

As far as your 1st question i am pretty sure that Event items are not listed in the rare sections as in the drop table pic below..

I do beleive like gathering you have Basic, Special, Rare

Basic- junk loot and silver

Special- Other category Mass,Dust Ect. (this would include event drop items)

Rare - Accessories (Disto)

I am 100% sure Event Items do not Affect the drop rates of rare items BUT and this is a major BUT they do replace them and other mats from the entire drop table i am sure another math junky could jump in here and prove it easily but a simple example is in the stars end drop table you have a total of 9 items that can drop one of them being rare and you have your basic Trash drop. Your biggest chance to get a rare is on that 10th mob were if your node is lv10 you get an extra 50% so basically you have a 1 out of 9 to drop that rare item Disto at .0001% thats like throwing a baseball at a slot maching arm in hopes of starting the machine to hit the jackpot BUT as a whole its still a chance 1 out of 9 items now lets toss in an event item or sometime 4 like right now...

Event drops current-

Hexahedron

300% Kyve

Afru

Boss(rare mob)

These above are also Drop event triggers (I.e. Branch for afru unless your in a party you personally dont see them but your party member can) added into the drop table the main issue is that now especially durning event's your chances decrease with each new item in the over all table from 1 in 9 to 1 and 13 this decreases the Disto drop chances even further than what they are now. The are most def not added into the RARE section but they will in fact decrease the over all chances of getting it.

Now on to the last question and i beleive you stated the correct one even though PA will never disclose the exact loot table and how it works but with 1000's of hours of grinding under my belt i have noticed a lot of trends one of which is the over all popularity of congestion of a grinding spot.

Stars end after it 1st came out was not grinded much becouse it was touted as the "END GAME" grinding area with 260 ap most back then didnt have a super high GS. So when i started grinding there i had access to every rotation just about 100% of the time for months i avg 1-4 Disto per day on a 3-5 hour grind there was never a time i didnt get one. Fast forward to when agris came out part of the questline was to kill mobs at stars end THIS is what changed stars end forever... PEOPLE realized they can grind there especially with the new class Guardian efficiantly So almost over night it went from one of the less populated grinding spots to one of the most active...

As soon as every spot became contested and the area became a complete waste of time to grind due to toxic players, DFS over population my Distortion drops went from 1-4 per day to one as in a single Disto drop every 15-30 hours. This would lead me to beleive that the actual rare drops are "POOL" related meaning that only so many are available to gain in a period of time and or the more "RARE" items drop the lower the % change to get them goes this also reflects in the market prices that pretty much remain fixed at 275-330 mil since they came out and have never changed no mater how many players grind there.

Tin foil hat i know but this would also explain a majority of the same type of inconsitant drops at every location and now the Elvia servers or Hadum area's dont seem to suffer from this becouse there is no "Rare" drop and no matter how many players i see grind there the money has remained consistant for me this is more than enough for me to continue to grind there. Anyway hope this helps.

We'll never get a straight answer from PA about this. Because PA doesn't even care to explain how stats work or how there calculated between each class. If they refuse to release that basic information for the idiotic reason that is "We at PA don't want to release these #s because we believe it will destroy build diversity an make cookie cutter builds." What build diversity there talking about is anyone's guess sense there not enough gear verity to even allow for build diversity. 

So ya if there going to defend not releasing that information with that BS PR statement they sure won't ever release the information for loot tables.

I don't think they will release it either.  However, there are many important facts when looking at the overall picture.

Class Vs Class modifiers were released

The modifications to these were released

(There is missing information on how much of a skills dmg is applied in PVP - *Reduced PVP dmg etc)

The hidden stats have as far as we know all been released.  Including ones that where hidden by accident because they where accidently left on the equipment).  The remaining equipment was updated to balance the extra crit dmg.

Drops where explained in the past in some circumstances.  VERY IMPORTANT ones and Pearl Abyss admitted some of their mistakes.  Investing in a node was NOT working long ago.  That was correct as we where informed on exactly how the node bonus is applied.

I know they released the stats on gear and multiplier for class on class damage. But there is clearly more to the formula we just don't know here. Like how does evasion vs accuracy calculate hit chance, how does DR calculated how much damage you mitigate, an what the AP and DP multipliers look like per class cause just comparing kuno and ninja togehter without their awakening or succ kits ninja clearly does more damage than kuno using the same AP, and same exact skills. So reall they gave us some #s yes but these #s by themselves are meaningless and don't help us figure out how they come together to get the hit rate, and damage per hit that we get each time we attack a target. An they can't give us a straight answer as to why they keep these formulas hidden it literally just some PR BS cause we all know there isn't any build diversity amoung the community it everyone go boss gear and stacks as much AP as possible.

So because they can't be honest with why they won't release thos formula they'll never be honest with us as to why they refuse to release loot table formulas. The only logcial reason I can think of as to why they refuse to release the formulas too is because than we start to figure about just how piss poor the game's code is when it comes down to how stats and how loot tables work.

Hidden stats have nothing to do with rng. They are just parameters which work deterministically. "Deterministically" means that at any given moment assuming the same input they yield the same result. Rng on the other hand is a complete opposite. If you get some item from an rng box, the next box will contain something unpredictable, but the input was the same.

This also means that not displaying the "hidden parameters" is just a matter of inconvenience. That's because since they're deterministic - their behavior can be reverse-engineered just by repetition and comparison (which gives rise to some external guides / web-sites).

The game has "some" rng percentages shown - like on enhancement - but there's no real way to check those displayed percentages. That's because for high-grade items it's impossible to do repetition and averaging en-masse to figure out things like probability density function or other statistical parameters. And why is it impossible? Because we're talking about items worth of 50+bil for say PEN accs, there's no way to have even a hundred of results (and it's likely that even 10 thousands won't be a statistically significant data set)

So despite enhancement chances being present - there's no real way to actually check it. On a contrary, when you fail a TET 30 times in a row with 20% chance, if you work out the math here, then the probability of this event is 0.12% assuming the uniform distribution. And when you have it happening to several items of yours - you start to really doubt those displayed percentages.

This topic and most answers in it can be simply and elegantly addressed by this:

Items for this event will not impact the rate of obtaining existing items

Source: https://www.naeu.playblackdesert.com/en-US/News/Detail?groupContentNo=581&countryType=en-US

As usual, no need to bullshit everyone with misinformation and conspiracy theories based on said misinformation.

Regarding global loot control, anyone applying minimal thought process to this matter would obviously know that if such a feature existed, being aware of it would lead to abuse therefore QQ from the very same people crying today about disclosure.