Is austerity necessary in Buddhism? I have been watching Buddhist followers for sometime now in India and it made me wonder if austerity is necessary in Buddhism ? 

Like if I wish to become a Buddhist do I need to give up on listening to music, watching tv, using social networking sites, making a livelihood by working in a firm, self- pleasure (read masturbation), have to sleep on floor and beg for a living?

I don't mean any of this questions in an offense way. But most of the people here, at least the common opinion as most of my friends/family have told me is that if you believe in Buddhism you have to live like a "Monk".
Is austerity [as defined above] necessary in Buddhism?

The answer depends as follows:  


As a householder, austerity, as you defined above, is not required since it's not part of the five essential precepts prescribed for him.1 However, this austerity, also know as the 8 precepts, is usually applied during retreats and Uposatha days.2  
As a monastic, it is required consistently since it will help to develop the meditation practice more effectively by diminishing unwholesome obsessions &amp; available distractions.


This distinction, however, is not "set in stone" or "black &amp; white" since householders are encouraged to follow this kind of austerity more consistently if they can and feel inclined to do so.