Doing business in US-questions

Hey guys!

I have a couple of questions about US law;

Can I operate and hire independent contractors, and pay them commission after completed sale - without having a company in the US?

I'm getting into the software business, and I'm getting a sales team through craigslist.

Instead of me starting a company in Nevada or Delaware; I could save about $500.

Or is it more credible to have a company in the US (with a P.O box and a skype number)?!

If you are doing business here you will need some type of business entity and you will be taxed (usually around 23%) on the US based income.