E commerce in the U.S

Firstly, I would really recommend you hire a lawyer that specializes in this domain, so they give you a thorough guide on what to do, when, and how.
There are many legal peculiarities about running a business in the US, especially if you are a foreign resident. And you want to know all those peculiarities right from the beginning because it will be too late to deal with them when you have troubles with the IRS.
Secondly, I would recommend paying special attention to the commerce cloud salesforce because its one of the biggest commerce platforms that provides numerous features, tools, and portals for growing your business.