As the title says, if all these assets are packed in the Vegas BSA's even if their not referenced in the Vegas GECK can reference and use them?

The Zeta assets are not all packed up in the Vegas BSA, else I would have used the crap out of them.

You can use anything that came with Vegas itself.

I'll check the BSA again to make sure, most of what I want I found in the BSA I unpacked ages ago.

You can use anything you want from Fallout 3 as well as long as it's only for personal use and you don't upload it.