There is very little difference in the size. I went from the note 7 to the edge and saw really no change other than the pen. But I have long nails so I just use them to write notes with on the edge.
As for best buy I purchased both the note 7 and the S7 edge from them and if you are doing Verizon payment plan there is no difference in cost, best buy does run a lot of bonus extras when you purchase from them. Corporate store are only able to do what Verizon offers you.