After reading *Chess structures* of Mauricio Flores Rios, I have some initial questions on the Isolani (or isolated queen pawn). 
The author shows this diagram:
[![enter image description here](https://i.stack.imgur.com/ETZra.jpg)](https://i.stack.imgur.com/ETZra.jpg)

Later, he proceeds to giving White and Black plans for the game. Here my questions arise. 

White is supposed to start a kingside attack. 
I can see no reason why one would do that. I mean White does not have a majority of pawns in the kingside. I would not clearly start doing anything on the queenside but I am not sure why I should do it in the kingside.

Furthermore, if the reason for why this kingside attack is justified does not lie in the pawn majority, I cannot see why the pawn distribution would allow White pieces to be arranged so as to threaten the kingside. White can place a knight on e5 but he can also put it on c5 so it is unclear to me.

I have this very same question also regarding the following pawn structure:
[![enter image description here](https://i.stack.imgur.com/5E6Qf.jpg)](https://i.stack.imgur.com/5E6Qf.jpg)

Later, the author suggests placing the Queen and a bishop forming an attack on the b1-h7 diagonal as well as a bishop on g5. These are reasons to start an attack to the kingside but again I am not sure why the pawn structure would suggest doing this.

My second question is why Black is supposed to benefit from the exchange of White light-coloured bishop. I can see this bishop supports the d4-d5 rupture but it seems somewhat exaggerated to exchange it simply for that (maybe there is a better reason?).