"why and when do we go for cds views"
CDS views allow you to push down complex data models to the database. They combine technical (SQL) with semantical (annotations) features.
"why and when do we go for amdp procedures"
AMDP is a framework for maintaining and accesing platform dependent database procedures and functions in ABAP. You use it, when the SQL of CDS is not sufficient.
"how will we give cds views and amdp to end users"
Applications or frameworks (like BOPF) written in ABAP access CDS Views with Open SQL and evaluate their annotations or call AMDP methods.
