I'll go first: (note--I use consciousness and awareness interchangeably).
1. Is consciousness limited to the brain? Why or why not?
This is the toughest question of all, I think! Obviously there is NDE and OBE evidence to suggest that consciousness is not limited to the brain. But there is also evidence to suggest that OBEs and NDEs may in fact be brain-based states. However, I believe that consciousness is not brain based. But its very hard for me to explain it. All our perception is brain-based so all our knowledge of the brain is also ultimately brain-based which makes it kind of an endless feedback loop-but awareness needs to be beyond the brain to be aware of this loop. Also, like Ramana, I have a deep belief that when the body dies, awareness does not die with it.
But I am also comfortable with a brain-based consciousness. Because ultimately, if reality is non-dual (and it is) then whether you are limited to the body or not, you are still that one self-aware reality.
2. Does consciousness evolve?
No. What you truly are does not evolve. Human understanding and sense perception may evolve--but not awareness.
3. What is the nature of the phenomenal world?
It's definitely not the physical, newtonian reality that we see. No one really knows the substrate of existence.
4. Is awareness related to sentience or is everything aware (including inanimate objects)?
I would say that only sentient beings are aware.
5. Can the phenomenal world exist without awareness?
No. Phenomenal reality appears to be dependent of our awareness of it. Sense objects, senses and awareness form a continuum. Ultimately, you can have awareness without sense objects (like in deep sleep), but you cannot have sense objects without awareness.
These are questions that have confounded the best of scientists and philosophers. But we can take them on here----no one can accuse this forum of being lightweight

Obviously there are no right answers---only diverse opinions, all of which are welcome here.
Oh and feel free to add your own questions too!