The 14th Amendment
Answer: every citizen has a duty to obey the law.
I'm not sure I discern a question here, but in a civilised society a citizen (I imagine you mean resident) does not have to believe in the law - there are several laws against which our instincts and feelings would rebel so (b) does not apply. Ignorance of the law has never been an excuse - so (c) goes out for a walk. The vote could be to change the law (d) fails to hold any water.
The First Amendment gives every US citizen the right to assembly and to have his voice heard.
A US citizen can practice law in the UK. They must first pass the bar exam and then get hired by a UK law firm.
To be Law Abiding
When present in the US, you are subject to US law, no matter what your citizenship is. There are exceptions for certain diplomatic personnel, but for an aveage citizen, US law applies. A US citizen visiting another country is subject to the laws of THAT country. I am a US citizen, and US law permits me to own and carry a handgun. If I were in a country that did not permit private ownership of handguns, I would be subject to arrest if I carried a handgun there.
The Naturalization Law of 1790
Foraker Law 1917
Every US citizen has it, it is guaranteed by the Constitution.
Yes
In the US, you must be a citizen to become a sworn law enforcement officer.