Yes, it is possible to host a social networking site on a shared hosting environment, however it is not advisable as it is a social networking website it should technically grow. As soon as the social networking site grows you will be forced to use VPS and Dedicated servers and grow from that point on. Take a look at twitter for example and their growth; regardless if you want to imagine twitter or facebook they are a good example.
To answer your second question, to start it depends on how many initial users you are expecting. Overtime this may need to change. This change could come over years or in a matter of hours. As far as all the initial things you will be required to start the process I do recommend you do some general research. It sounds great to make your own social networking website however its not as easy as we make it seem. Somethings you need to look into is the name, who will join in the beginning, where are you getting the financial requirements when/if it grows, and much more.
If this social networking site is going to be built for college students of an individual college and you expect 100-200 users, a 10-20gb database should suffice for the first 3 months, however this is an estimate and may be different depending on how the script and database is being used. Remember that as more users and more content is added from the individual users the database will grow.
Other things you will need to look into is web space; in your social networking website are you allowing people to upload images and videos? if so; what is the limit per user. There are many more factors you will need to look into.
so what u guyz think ( i m in india)
so what should be the ( i m asking abt only website developing not any webhosting nor any other thing ) just a website where every thing is limited right from uploading photos to sending friend request as we are just a starters ....so what should be the cost of developing this kind of website
we have a budget of 130$ (in india 1$ = 45 inr) so what u think will this amount will be sufficient just for making "social networking website" ???
we are engg. students