I am planning to start a social networking site for college students to date, chat, sent free SMS , call, play online games and create virtual tours of college to show where you met your love, your college etc. and also create virtual tournaments.
Privacy to messages, groups and friends will be given.

Exchanging pictures,videos and music through mobile at a go will also be available.

Well as far as it being a competitive market… That is true… Most of the things you listed are already available on other social sites. You need a niche. Something that you can market. For example I just started a new social writing community at http://www.freedomspress.com
I quickly realized that this was a tough market especially since the new age of blogging. So what can I offer people that other sites can’t? Well not much to be honest… But I can reinvent an idea. The idea of offering a service to people without a whole lot of computer knowledge. I stripped down the service to make it easy and dummy proof. You need to do the same. But keep in mind that the tough part is getting members. Why should people join when there are no members? Would you join a site when you are one of only 5 members? A way around this might to plan in stages… Don’t start off as Disney Land when you have only 5 park guests. instead start as a local small town fair. What I’m trying to say is if you have a never ending site with tons of options and pages then it might make the user feel as if they are alone on an island.