Can the authorities disconnect a server from the internet? And how?

[benon]

I have a couple of questions (I'm sorry if they are stupid):

(1) Let's say the US government wants to remove a specific server from the DNS, which it was proposed to be allowed to do in SOPA. Doesn't that mean they would need to remove the entry from all the root name servers? Many of which don't physically reside in the US and therefore are not subjected to US law? How would the government be able to do that? Or does it suffice to remove the entry from just some of the root name servers?

(2) Let's say a server uses a domain that is under an alternative DNS root, like dotbit or openNIC. I assume the authorities can find out the IP adress of that server. Are they able to use the IP adress to find out which ISP provides connection for this server? If the ISP is a US resident, can they force the ISP by law to stop providing service to this server and disconnect it?

(3) I assume that if the ISP is not a US resident and the server isn't on US soil, the US government can't force the ISP to disclose any information on the client or disconnect the client. Can the government, however, use the IP adress to somehow find out the physical location of that server and physically disconnect it and/or destroy it (aside from any legal or political consequences, let's say as a secret military operation)?

(4) As an example, let's take the Silk Road. http://en.wikipedia.org/wiki/Silk_Road_%28marketplace%29

I assume that if the government was able to shut the website down, they would, because it's a marketplace for drugs and weapons, among other things. I also assume that anyone can resolve the IP for this server, because, I mean, how else would anyone get there (if I understand the internet right)? So why is the server still online? Is it because both the ISP and the server reside in a country that doesn't wanna take down these sorts of servers? Or that the IP adress can't be used to find out any information about the server? Or what?

Thanks so much for your answers!