you seem to have a lot of questions concerning the legality of using assets from someone else's mods w/o their consent...
The third one is this: https://www.beamng.com/threads/volkswagen-scirocco-ii.36778/ or i think it is. and you can find a fixed version of the helicopter in drowsysam's discord server.
The big wheels are a repo mod, or rather several repo mods for big wheels of various sizes. The saw wheels are a private mod that just replaces wheels of some mods with saws, probably low quality. The Baserunner mod, I have no idea what it is, but it's private and definitely not a meshslap. The train mods are made by another youtuber who has several channels, and he only gives them to Wreckstation for some reason. (I think his main is Crash Game Channel, but not sure, it's a deep rabbit hole to figure out who owns which channel in that sub-community) The car crusher is an extremely old outdated mod that doesn't work anymore, idk how he has a fixed version. Idk where he got his private crash test dummy, but that seems to have completely different Jbeam than the public dummy mod. For the rest of the mods I have no idea but I assume they are private. Youtubers like this often prefer paying someone to make a mod than downloading from sketchy sites, I'm not sure why. Fun fact: He is the only one of big crash compilation youtubers who uses a different style of profile picture, the others have "ripoffs" of CrashBoomPunk's pfp which he had since 2016. (Unless BeamNGTV counts too, but he makes more than just crash compilations.) WreckStation's channel is the oldest of them too, dating back all the way to 2015.
as far as i know they are all owned by the same guy, the guy is actually nice though, he has given me something in the past so atleast he shares some of his stuff