Yes.

Well, I don't know about traveling the cosmos without harm. I have never been bothered to do that when I have experienced it - and I couldn't possibly verify it was genuine if I did do that. But there's no reason why it should come to harm - since it isn't physical.

Unfortunately, I have yet to come across a method that can consistently allow me to experience out-of-body or astral projection. So most of my experiences in it are when it randomly occurs beyond my conscious desire.

My answer to both of your question is, yes! Given, our spiritual essence is separated from our physical body, no harm is done. I have had many experiences whereby I am some where else having a live interaction, but then suddenly I would realize that I am laying in my own bed.

maybe travel your specific perception comprehended of the cosmos but....... not to sound negative I would think not. then again anything is possible so I should be more open minded.

Since the human body is purely a physical entity and therefore has no "spirit" that can leave the body - then astral projection can only be seen as an imaginery or dream like state.

Nobody has yet scientifically proven astral travel/projection within a lab environment.

I understand James Randi, and other similar institutions offer cash prizes to anybody claiming to have super natural or spiritual powers, (mainly focused on "mediums" but I'm sure being able to leave your body would also interest them). So there is some good money that can be earned for anoyone who claims that they can do this kind of stuff. Alas, all cash prizes are still unclaimed.