I don't know the answer these questions myself. You might.
What I do know is that in the Bible, Elisha, who had a double portion of Elijah's spirit, died. And when some morons dumped a dead man on top of his bones, that man came back from the dead. Was there a spirit still in those bones or did God consecrate the ground where Elisha was buried?
Or when Moses struck the rock with his staff instead of shouting at it to bring forth water. It worked, despite his disobedience, so it was as if he had some autonomy to use his spiritual portion as he saw fit.
Our bodies aren't exactly supposed to be regarded with contempt either. Paul writes that our bodies are temples to God. And yet so many fools have Type-II Diabetes. Not to mention Monkeypox. And if you can't overcome gluttony or lust, how can you expect to escape Purgatory?
On top of that, Jesus Himself gave up his spirit but come back in full body from the dead. His Spirit was strong enough to support a body dead for three days and still full of holes. That last part might have been told in jest on his part for Thomas.
So what is the link between body and spirit? I really don't know and the Bible only gives us clues. I can't trust modern interpretations because theologians are largely full of themselves. Ancient Bible scholars don't seem to have the answers either.
Maybe it's just mystery to never be solved with wisdom. Or, more likely, I simply lack wisdom to properly understand it all.
Either way, there is more to the link between spirit and body than I think modern and post-modern thought understands it.