The confusion about jsp four scopes and ServletContext,HttpSession,HttpServletReqest,PageContext

The jsp four scopes are same with ServletContext,HttpSession,HttpServletRequest,PageContext?

How servlet is initialized by servlet container,is also order?

In a jsp or servlet,getSession method  what can get, and how could put variable into scope(How do declare scope for variable?)?

Now they are my question,go on.......................................................................