When I went into Barlay's to open an account they said that had I been in the country for less than 3 months, they could have used my US address, ID, etc, but because I'd been there 4 months, I had to have proof of UK address which, of course, I didn't have.
As for the BofA/Barclay's thing, I'm not entirely sure what the relationship is either, but the upswing is that when you pull cash out of your BofA account using a Barclay's hole in the wall (ATM), you don't pay any fees. It is purely the exchange rate. Otherwise, and this part I'm fuzzy on since I've always use Barclay's, there's either a percentage or flat fee for making a withdrawl. If you use your BofA debit card to make a purchase somewhere, the fee is even higher. Different rules apply to BofA credit cards; I don't have one so I don't know what they are.