When is the best time to apply for internships?

I am a B.tech 2nd year Mechanical Engineering student and I wanted to do internships from foreign based automobile companies.

When do companies like Google, Microsoft and Facebook start hiring summer interns for summer 2014? What is the timeline? How many months does the hiring season last?

Variables that affect answers could be prestigious of the companies where you will be eventually working at and, alternatively, the reputation of the University. Let's assume we are talking a 60+ employee company (40K/year) compared to one of 50 greatest...

e.g. If it says "Required: 2-3 years of relevant work experience" on a job description, and one were to have several internships under the belt totaling 2-3 years, would that be equivalent?

I attend college part time, and it offers many internships, for my specific career, which I could potentially get a job at after I graduate. I'd really like to take advantage of that, but I can't survive on a part time job so would I have time to complete...

This mostly pertains to software engineering, but maybe it can be applied in general. I know the work done is more important than the title of the position, and I understand that internships are set with begin/end dates while part-time jobs are more...

For those who passed on gap year, there'll never be a better time in life for this kind of thing. It might be the last time it's even possible. The costs of taking time to backpack around the world only increase. Still, there are costs. How important...