I am not sure he would get a visa as a contractor.
Also, as a contractor, he would not get health insurance.
Setting up a company is a way of limiting your liability and getting yourself an income as the employee of the company. It would be sensible. But he would need to get a lawyer to help set it up, and this would come with a cost. Tax-wise, he might write off a 'company vehicle' and claim other expenses such as cost of a dedicated work space at home, laptop, phone, etc.
Simply moving and getting set up would cost several thousand £. Apartments (apart from corporate long-stay apartments) do not in general come furnished in the US though you would have a fridge/freezer and dishwasher included in the vast majority of apartments. You would need to rent or buy beds and bedding (US and UK standard sizes are different), and furniture. You would need small appliances - hoover, kitchen appliances (coffee machine, mixer, blender, electric kettle, etc). You would also need to fork over at least a month and a half in rent up front, followed by your first month's rent in advance. Can you afford to move, given that you have no income right now?
You would need to establish credit before you could buy or rent any of these. While this can be done by getting an Amex card and paying off purchases in the UK, your H is unemployed at the moment, so this might be difficult.
Without any financial or practical help from the company, all of this would be a burden for you. You would be looking at considerable outlay and considerable effort on your part. Would they even offer help finding an apartment? Or would you have to take a trip to find and meet with a leasing agent, look at apartments, look at neighbourhoods, and fill in forms consenting to credit and background checks by potential landlords. There is a lot of expense involved. If you went out and stayed in a motel while looking, you would put yourselves in a very precarious position, with the motel bill to pay, and the possibility that your foreign references and credit history would result in landlords saying No thanks. I can see you hemorrhaging money just getting out there and getting settled.
And then there is the massive difficulty of health insurance. It might swallow a third of your monthly income.
Quite honestly, I would be looking much closer to home if I were your H. Could he work away weekly - in Ireland, Netherlands, Germany, Belgium, France, Sweden?
Also, if you do decide to try out Dallas, you really should rent out your house in the UK. How would you afford the mortgage, council tax and house insurance otherwise?