Here's a really dumb idea about the portholes: they're literally just temporary access holes poked through the side of this structure because they can.



As many have said, this is very clearly NOT the final orbital design, just a test article with crazy margins and design/construction techniques. Maybe they needed some access holes, so they just cut some holes, and intend to "patch them up as good as needed" for the test hops.



(I also think they are more probably for RCS (new methalox thrusters, not draco/superdraco) or possible even fin/canard/brakeron/gridfin thing attachment points)