1) You can always try like a Merrill Lynch type compnay for financial planning advice and one of the Big 4 Accounting firms for accounting advice. Again, the bigger the company = more expensive, but it would be one stop shopping.
2) See I think you are making assumptions here. There is nothing I can think of off the top of my head that would make the transfer to a UK account any different than transferring to a US account. I think it is absolutely possible to do this. If your current company has UK branches, than I would start by talking to them. It could be relatively easy. There could be one thing to complicate the issue, so I won't say for certain either way, but don't make the assumption that it can't be done.
3) Broadly speaking, the UK will not tax your US funds, because you are a US citizen/resident. Even if you live in the UK (and will then be a deemed UK resident), your US earned income won't be taxed.
4) You can transfer the cash, period, and the transfer itself shouldn't be taxed. If you want it to just go to the bank account, that will work. If you want to invest it in an offshore account, that will work. You can do with it what you want. You will be taxed in the US on whatever capital gains issues arise (gain on investment, gain on sale of residence - if applicable), but the transfer won't be taxed.
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If you are still in the US, I would get some financial advice beforehand. Go to an accountant. Look in your area for one of the Big 4, or a large regional accounting office. Depending on what area you live in, I could recommend a decent company.