What are the ways a foreigner can work in the US and how quickly are they able to?

Question

For instance, can they come to the States on a visa and work as an independent contractor?

Answer 1

Nop, You can not get a Visa and work as a Contractor.

You have to get a sponsor company and let them get your work permit. Unless you have lotssssssss of money then you can apply as a Investor and get a Visa, but that needs to proof you have a lot of money to invest in the US and you are gonna generate a minimum amount of jobs.