Pixelhate

"out of the total combined Adjusted Asset count of 54,930 files, 18,008 are common to both games" Here's an excel spreadsheet showing the asset differences between Fo3 and FNV https://www.nexusmods.com/newvegas/mods/34774

You might have more chances for an answer in the VNV Discord server, they have a Linux help channel. https://discord.gg/S99Ary5eba

Texture animations.

I would look at a Vanilla nif similar in weight and size and copy carefully all the necessary settings in collision. More about Collision types & settings, part 06A, B & C https://www.nexusmods.com/newvegas/mods/76374?tab=description and https://geckwiki.com/index.php?title=NIF_Block_Types#Havok

Yes this is normal, grass placement is done at runtime by the engine.

In NifSkope: https://www.nexusmods.com/newvegas/mods/76374?tab=files Part 06A, B, C In Blender: https://www.nexusmods.com/newvegas/mods/76324?tab=description

Yes.

Furniture will crash if TextureSet is used. You need to make a new nif with the new texture.

https://www.nexusmods.com/newvegas/mods/38153

I can only concur with what MadMongo said and suggest you to have a look at https://www.nexusmods.com/newvegas/mods/76374 to get the basic of a nif structure.

Does checking "Persistent Reference" help?

Also make sure to use the Geck Extender. (Hi MM )

Answers are in Bits of NifSkopery part 03B

NVAC just tells the game to not crash, it does not fix anything, so you have to live with any side effects of game not crashing when it should have. So it will allows you to play with a bad conflicting mod list by preventing crashing till game is unplayable or save is corrupted beyond repair. On the other hand, it will prevent a correct set up to work flawlessly. That's why it's not recommended anymore in those guides. That said, if you plan to make a play-through with mods that are known to cause crash and have no fix, NVAC is a must CASM is replaced by fucntions found in Stevie's tweaks which is a must have. https://www.nexusmods.com/newvegas/mods/66347

This is the place to start any serious setup: https://vivanewvegas.moddinglinked.com/intro.html