What a wonderfull text!
What I like to think about all questions you made can be ilustrated by a short story I wrote:
Imagine a table with four people and a super microscope that can see our atoms.
If it makes a section crossing by the arms of the People, the image Will be like an universe.
The air is less dense and the People is more, só, each person will look like a galaxy and in between them will remind the isolated planets and stars.
With this idea in mind, add the concept of universal interdependence of all existent materia and its constant exchange.
Thats it. For me, call us as an organism is really appropriate.
Life has no meaning and god’s existance is not going to change anyone’s lifes.
What do you think?