These threads also exist:
http://originaltrilogy.com/topic/Why-Leia-remembers-Padme-but-Luke-doesnt/id/3834/page/1
http://originaltrilogy.com/topic/Could-Force-Vision-explain-how-Leia-knows-what-her-mother-looks-like-Discussion/id/47742
The scene of Padme dying was a writing screw up on George’s part and if you begin to start twisting it all in your head on how it all makes sense then your taking it too seriously and need to take a step back.