Help with Sony Vegas

you can dublicate your layers by rightclick on it --> dublicate.
And yep, you can resize it, without loosing the motion tween.

To group layers? Im sorry, but thats a good question. You can creat folders, but i don't think that thats it what you want ^^

I was wondering if I can resize multiple layers at once, so I asked if it's possible to group multiple layers together.

So if the group is resized, it's essentially resizing all the layers in the group at once. Hopefully you understand what I'm trying to say?

If you know any method that might be similar to this, please feel free to tell me it

Though, I've been appreciating all your help!

P.S.
Actually is it possible save the whole project and import it as its own layer?