ShyTorque
that is not strictly true... there is a joint taxation agreement between the US and the UK. You don't get taxed twice and frankly it can be quite beneficial if you are paying tax in the US. I get credit for paying tax in the UK and the US with both authorities. I get a nice cheque from uncle sam most years based on the tax I still pay in the US even though now UK resident. For example I can use my wife's tax allowance as we file jointly and my offspring are tax deductible. It either feels unfair at times or very generous and I am sure it is just there to keep accountants out of trouble
You can relinquish your us citizen ship but it is difficult. My daughter for example is a us citizen and has had to start filing tax returns at 16 to maintain her obligations and enjoy the benefits of both worlds.
Regarding Scotland, I would imagine it would be a no brainer to have the same arrangement with the UK and as above the individual both exchequers will manage it.
Regarding the EU and scotland, I can't seeing this being as easy as Salmond makes out. There are so many independence issues in the EU that I am sure it will set the wrong precedent. i.e. Basques and Spain, Danzig etc and not forgetting if the desire for Turkey to join is still there the Kurds. Not forgetting the mess that is eastern europe who have their own issues.
The only good news is the lothian question is sorted out once and for all and english MPs can decide what happens in england. It also makes it harder for idiots like Miliband to get in and it might bring back some conviction politics back.........
Frankly I don't think this has at all been well thought through and if the scots do go there own way... be careful for what you wish for.