Starting a business from the UK as self employed, with an eventual goal to employ US Citizens and move to the US to work - possible?

I'm currently working on building an online business based around travel and tourism and eventually I'll need to employ people in the US, located in a specific area. The end goal is that I'll be able to work in the US on this as it will prove very difficult in the long run to work away from the place this specialises in.

Am I right in thinking that once established I can employ US citizens and would be allowed to reside in the US so long as the business continues to employ US citizens? It wouldn't ever be some huge mega company, but I'd expect to be able to employ 2-3 people not including myself.

I believe there is some form of US visa for startups isn't there?

There are multiple visas that you can apply for. There is the L Visa, E5 or EB-5 Visa, and also E-2 (Treaty Investor) Visa for which being a UK citizen you may qualify. So I would suggest reviewing the requirements and possibly consulting with an Immigration Lawyer in the US to actually see what you will realistically need to do.