Is it possible to develop forum site using blogger's free hosting facility and what types of difficulties have to face?
Yes you could with blogspot, they have an option for you to use your own domain pointing at the site hosted there. Also you could use a .TK domain name to point there, and .TK is for free.
You can add a forum in blogger free. Below is the link how a add a free nabble forum in blogger.
Thanks everyone sharing your valuable tips and views.