@Manasi29 As regards your second question, it depends on what kind of
Components you are building for different Pages (Sling models are
recommended for Components, where you are writing backend logic and you
want it to achieve it with writing less Code (organized, modularized,
short, and concise)). Coding components with sling models is the
recommended AEM best practice from Adobe, as demonstrated by the
implementation patterns in WCM Core Components. Please go through the
above URLs I highlight...