Through is the preposition and window are the object, I believe.
An opportunity to seek vengeance on their friends behalf; the socs wanted to avenge Bob's death, and the greasers wanted to settle the score for Johnny.
Also, the lot is a less conspicuous place where they hoped cops would not break up the fight. Moreover, the lot is convenient for the greasers in terms of location because it's their neighborhood.
It is a matter of individual will power and the ability to fight against the odds.
Explanation:
While the way one person responds to adversary conditions has a lot to do with their situation of privilege against the adversary, it also has to do with the way they are conditioned as people.
Some people react better to such conflicts because they are either used to facing such high pressure situations or have mental fortitude for it.
It is also to be considered however that different things affect people differently and there is no way of knowing how one would react to such situation when it comes to it.