Rail Track part-2

I don´t get the logic of not doing it in the endgame because Bishops are supposedly more use there (I presume he means the Bishop pair in an open endgame). If you´ve already done it in the opening, then you don´t have any more Bishops to do it with later, unless you´ve underpromoted a couple of pawns by mistake in the middle game. And if Bishops are supposedly going to be more use in the endgame, why exchange them in the first place? Or have I overlooked some mate in 3 with the Knights on move 15?

Don't get this "rail-tracking" business in 3-D. Would definitely end up throwing away bishops thinking they're pawns. Need a fresh look.

I really don't understand. You give up both bishops in the first 9 moves and what is your compensation? One set of doubled pawns? That's it?!