More likely that the Raider opened up on her at point blank range...
6x6-inch guns and her torpedo tubes can do a lot of danage at point blank range
Yes, and that explains why she sank - but it doesn’t explain why there were no survivors.
Kormoran and Sydney moved apart after the battle, both ships badly damaged and doomed. Sydney was last seen from the Kormoran down by the bow and on fire, but there should have been plenty of time for surviving crew to have abandoned ship.
I agree... they did at Wake island to a Jap surface fleet that was in full, invasion mode. IMO... HMS Sidney paid the fatal price for underestimating the guile of her enemy.