I think the biggest thing is that Palp was using his Sith ability to bring Luke to the breaking point. Of course the station was not FULLY operational. Much of the internal superstructure of the Death Star is storage and housing for ships and other vehicles. Of course that stuff wasn't finished. That much is apparent right away in ROTJ. Jerjerrod (however you spell it) didn't know Vader was coming, and was complaining that the Emperor expects too much with so little work force. That's when Darth Vader pimp slaps him and said "Make me some pie woman." Well...o.k. maybe not, but it would have been cool.
We know from EU sources that most of the Imperial fleet retreated. Those who stayed behind had it handed to them on a Mon Calamari silver platter.
And in closing I feel I must say "Jar Jar blows."