I can answer some of these...

1) dead growths are tanks, null pointers are witches. the number increasing is how much you have killed.

2) well, there are things like uh... Bull-True. Dead Eyes and Quick Draws. Bull-True for when you kill a charger when it charges. Dead Eye for killing a hunter in mid-flight. Quick Draws for when you kill a smoker, when it has just ensnared you.

I thiiiink, although I'm not sure, that's what the tests mean. each special infected is a test. or maybe if you complete the fightback sequences successfully, you'll get the test number up. all this is just speculation, I don't actually know myself.
I think Resillience Tests specifically, are exactly how much you have gotten bull-trues, deadeyes, quickdraws.


3) I have no idea... maybe it's bugged? or maybe hasn't been implemented that much yet? same as Danger Rating. Danger Rating, I think, would've shown you a grade. A, B, C, etc. comparing to how much you have killed, and could have killed (maybe). regular infected, special infected, tanks, witches. you know.

4) not sure about things being sent in chat, that hasn't ever happened to me. what was being sent?
some console commands don't really work. like the one that is supposed to bring your voicelines back, at least for me. but others do work. some work some don't. coding is hard.

other things happen randomly I've noticed, so maybe it rarely happens? the black screen, that tells you to pick up the phone, appears for me sometimes, and sometimes it doesn't for the entire duration of a campaign. once it appeared only 40 minutes in.

I've played as ellis one time, and suddenly it was static. ellis spoke and grunted in pain, like uh... "this ain't right" or something. and then I heard nick surprisingly, calling out for ellis.
it ended with black screen, and nick mourning ellis. then the gameplay resumed. that was quite neat to see.

The video I saw mostly just said some stuff about picking a survivor with E, typical tutorial stuff. The video I saw was the one by Zelancholy, the one with 23k views at the moment.

Also, I've not encountered anything like what you just said at the end, i've seen the screen about picking up the phone, but the only voiceline that comes up is someone saying "Sorry". I think it might be Ellis, but i'm not sure. It seems to happen after I heal for some reason.

hm, well I haven't had heard anyone saying sorry. maybe that's something I have not yet seen? the thing I spoke of, I've seen it only once in my whole time of this mutation's playthroughs, which is like... several games, ranging from 40 minutes, to an hour long play lengths. so there's a lot in the mod that one can probably see later on. probably but idk.

one idea is to use host_timescale command to speed the game, and see how long it takes for any of the stuff to happen.

gotta watch that Zelancholy video, see what it has.

another interesting thing that I've done, is uh... touch TV's 3 times. some text appears, I don't remember which, then youtube links for each one; which, for me was showcasing the powerups. bull-true and others.
though when you get the 3rd TV, your textures disappear, everything stops, and then you get jumpscared by a woman's scream, and the game crashes.

now that I've watched the beginning... I think I recall seeing the tutorial in chat. it has appeared when I first started playing the mutation. like the first time ever, and it hasn't appeared again ever.

I didn't even get that. I had to figure out that you had to press R to transition between maps.

dang well frankly that was the same for me. at first I waited for it to do it automatically, but it didn't after a bit. so I had to press every button until eventually I got through. idk why tutorial shows up for some, and doesn't for some.

Donno either. Also, figured out why the ladder on the roof in the finale of No Mercy didn't work when I tried.

Turns out the game blocks the exit to the roof once you go up it, and if you go up it in that weird state where everything's frozen before the level actually starts, you effectively softlock yourself. I guess there's not really much that can be done about that considering that's how Valve made it.

ooh ya, good observation, I think I've had that before too. I just used noclip after that, cause that's bs.

I didn't, because i'm trying to beat every campaign in L4D2 using this mod and recording it, and it just wouldn't seem right to use noclip.

fair enough