It could be done, but it will be much easier if the populace is disarmed.
As a matter of fact if this group is as international and powerful as the author asserts, the same could be could be done world-wide.
Yes it could, once the USA is under their control.
As to your other question, globalism is happening at an ever faster pace. Sure, the US government could implement it much faster but they recognize the fact that the idea is still strongly opposed. Therefore they're taking it slow and easy, exploiting every little crisis. Calling for national ID cards in the wake of Sept 11th, etc. Little by little they take a little more ground. A little more liberty.
Recently, Congress gave the Executive Branch the power to "fast track" trade agreements. Look for Bush to use this newfound authority to enter us into something like the European Union. Of course Congress gets to vote on anything he proposes, but I wouldn't expect them to really vote anything down. We're on the way to having one currency for the entire Western Hemisphere (exept Cuba maybe). Get ready to pay off some serious Third World debt, Mr and Mrs Taxpayer.