It's a zipper with white bias tape. Take a look at my pic here:
I used a white zipper with white tape, then on the top of the lapen i used white Bias tape.
If you look at some of the male students they have the blazers zipped up. And they zip on the side for some reason..And as for not seeing a zipper on the other side, do you see the white stripe on the left side of his coat (right side on mine because it's a mirror pic)? That is the other zipper. The right side folds over the left
As for the tie, Use 1/4th in black ribbon and just tie a simple bow like a shoe..