Regarding point(3), if you kept "principal" and "income" seperate in the US, you could remit just the principal part and not have to pay tax ?!
Guya, are you sure about (5) ? I have met with 3 different tax attorneys in London so far, and none of them even so much as mentioned the exchange rate advantage being treated as a gain. This is money that is coming from US to UK for the first time (not money that was in pound sterling in the UK, got converted to US $ and then bringing it back, in which case I can understand ...)