Hi Sankar
As an architect you are free to design in a way that you see fit. Just remember that you need to justify their decisions. So there's no way to answer this kind of question.
For example: I disagree with you:
Stateless SB can't be business layer! If you do your business layer as Stateless SB, you'll be tying the rules of business of the solution in the
EJB technology. In my opinion as an architect, a business rule should be written in
Java as Pure POJO.
As I told you, every architect has their point of view.
If you need to study design issues, I advise you to read books on the subject:
1. POJO in Action Book by Chris Richardson Book.
2. Domain Drive Design by Erick Vans Book.
3. Patterns of Enterprise Application Architecture by Martin Fowler Book.
Best Regard.