Wow! That was time well spent!
Just in case you really need the answer to your first question...
(Is suspect you already know the answer) the BC stands for black color, which at the present time is the only color the PRS-700 comes in. You'll see those additional letters behind the name of the PRS-505, as they come in 3 different colors.
Welcome to the forum! Enjoy the PRS-700! I love mine!