Not sure of the reason, but I believe a US resident can simply open an account with the euro-division if s/he wants to use the other platform (there used to be a commission difference, but now they're both $30 per mil USD). They should just offer both platforms to clients of both divisions (as it's the same underlying ECN), but they don't.
Most likely, but probably to the tune of 70-100ms extra. Only an issue if high frequency scalping. Otherwise, rested orders typically remain on the server-side.
I am under the impression there is only one server (one for retail and one for institutional) - at least the prices are exactly the same. Executions 'feel' almost instant, i have no means to measure it exactly.
Its actual trades. Bid/Ask updates would have dozens of updates each minute. Still dont understand how this information could be of any use at all.
You don't understand how volume can be of any use in determining when to get in or out of a position?
No, tell me, what information could you possibly deduct from a few T&S prints on a single FX platform out of dozens (a retail platform at that).