I don't know the answer in its entirety but 1. is apparently discussed in yajur veda. Regardless, I'd like you to think about the following.
Vedas were not divined in the kali yuga.
The different varnas came into being in different yugas. Narada explains this in Uttara Kanda of Ramayana.
Vedas embody universal truths that endure across time and space. So if something that is a kali yuga phenomenon does not appear in the veda, it does not mean the veda is wrong nor does it mean that the yuga dharmas are invalid. It is precisely for the changing yuga dharmas that smritis were born. And these smritis note the practices that are to be upheld by various people during various times.
Even within a certain yuga, if a certain phenomenon is unacceptable, change does happen within that yuga itself. It does not render the Veda or the change invalid. As an example, are computers mentioned in the veda? (although this is a favorable kali yuga change)
So the lens of "if it does not appear in Rig Veda, it is false" is really just a blinder with a very tiny aperture.