@Bingowings
well I had the impression that the Executor would be about 10x the size of an standard Stardestroyer, bringing it to somewhat 16km
but in the end it just needs to be "huge" ;-)
as for the "Leia's mother / Padme"-Paradox: it all stands and falls with Luke's question "do you remember your <real> mother?"
if one would cut that out, it just states as to why her foster-mother was sad => because she knew what happened to her <real> mother ...