no
A company has to sponsor the Mexican to get a work visa.
A US citizen would have to apply for a visa and become resident. Alternatively they could marry a UK citizen. In addition a British Company could invite the US citizen to work in the UK and apply for a work visa on their behalf. There are quite a few ways to do it legally.
A "visa" is kind of like temporary citizenship. A "work visa" allows you to work in a country you aren't a citizen of, and a "visa" allows you to live there.
No. Having a visa for country A will never work to get into country B -- anywhere in the world. In the case of Mexico, you need to get a visa issued by the Mexican government.
It is better to get a working Visa in the USA. A BCC won't clear the reason why you cross the border every day to go to work. Also, working in the USA is illegal if you don't have a work Visa
No you will not become a Mexican citizen but you will have Mexican recidency. Your fiancee can have the option to apply for citizenship later on if she wants.
You should send resume to a company that might need a person with your qualities. The company has to be a legitimate, tax paying company. If they approve it, they will sponsor your work visa and you can come to workd in the US.
I'm not sure on the particulars but, my father did this for most of his life. It is quite easy for a Canadian citizen to get a work visa in the United States. Contact immigration they should be able to give you all the information US employers can sponsor work permits for EMPLOYEES, never for non-employee contractors.
It isn't just for TNA, if you are not a citizen of the USA and you want to work here you have to have a Visa
Work visa can be got through employers only. Either company in US should recruit you and apply for your work visa or company in your home country also can send you to work in US on a work visa. Depending on the requirement and your eligibility you will be issued a visa with which you get authorization to work in US.
You would need an appropriate work visa in that case.
She would need a UK work visa.