I currently in SE Mechanical in Sardar Patel College of Engineering, Mumbai.. I've seen that many students opt for internships after Sem-IV.. I have some doubts about these internships..

1. Why should we do an internship? Does it add some weight to our CV when we go for placements?
2. When should we do an internship? When is the correct time to consider doing an internship?
3. Where should we do an internship - in a big renowned company or a relatively smaller firm?
4. How can we apply for an internship? Should we approach the TPO of our college or find out on our own?
5. What do we do in an internship? What is the exact structure of an internship?
6. How much money do we have to spend to do an internship?

I hope people here can provide me satisfactory answers or at least ways to find them.