That is not how international taxes work. If he doesn't maintain two addresses and treat the UK one as his "domicile", he will only owe taxes in the US. There are also bilateral treaties that cover this and, for example, retirement accounts.

What is a travel visa? Presumably OP has a UK passport and would have a US work visa, which is attached to an employer. He also doesn't need any visa to enter with a UK passport-- just needs to fill out the ESTA application.

Do you mean a work visa? Generally companies that pay you a quarter million dollars per year will cover the $10k of relocation fees and the filing fee is trivial compared to the mood. However, OP, any relocation cash you get from the company is considered taxable income (thanks, Trump). He also doesn't need a lawyer unless something goes terribly wrong.

Either way, I would definitely get a tax accountant, OP. In general, the US system is incredibly complicated and the accountant will almost certainly know of deductions that I do not know of and more than pay for his or her fee.

This commenter has no idea what they're talking about, OP-- literally everything statement they made was false.

And the answer to this commenter's question about needing to live in NY is a solid "no", but I suspect someone who makes $220k doesn't want to spend 3 hours commuting every day when they could very easily afford to live wherever the fuck they want.