According standards

U can learn accounting standards from any modules or reference materials from ICAI or any authors book.

Regarding importance, I would say all AS are important, depending upon ur view point. Like you are looking at the  from exam point of view or from learning point of you.

I want to learn it exam point of view.

 AS 1 AS2 AS3 AS4 AS5 AS6 AS7 AS9 AS 13,14,16,19,28,29