Visa for applying to a US firm
If a non-US resident applies for a job in a US company, under what Visa will the US Company sponsor him? If it is H1B, isn't the company limited by cap? If it is L1, doesn't the applicants have to be already working in that company?
You need to talk to the recruiter first. They might be able to employ you at your home country if they have an office there until H1B is approved next year. Or maybe they can ask you to apply to the office in your home country directly. Not saying that it will likely happen. So it's better to talk to the recruiter first. But you cannot come to the US immediately. Unless if there is any other visa that I'm not aware of other than H1B and L1.
Marry someone who has already settled in the US. Don't know what type of visa that is.
Yes to all your questions.
So even if I clear all rounds of Facebook US offices and I do not get the H1B, Facebook will reject my application?
Yeap