Understanding Asa ki Var

A few questions about Asa Ki Var :

1) What is the purpose of this bani?


2)What is the best time to do this bani?

3)What are the rules to reading this bani? (i.e can we stop at pauri and continue, stop at each chakka)

4) What are rules for when it comes in a Hukamnama

5) Are there any sakhi's regarding Asa Ki Var that sitck out to you?

6)Where was this bani first recited, and how was it compiled

a sakhi i remember is of guru gobind singh ji. when guru sahib left anandpur sahib, even with the enemy behind them, they began asa di vaar