1. No.
2. You can actually do both.
3. The basic idea is if you leave the United States for less than six months at one go usually you are okay, you are not questioned too closely, but more than six months they question you very closely because of certain technical reasons.
At one year outside you lose your green card automatically unless you have something like a re-entry permit. If on the other hand, you are a U.S citizen there is no requirement that you have to stay in the United States. You can stay anywhere in the world, never have to come back again and you would still be a U.S citizen.
Note: Where transcribed from audio/video, this is a verbatim transcript of the referenced audio/video media delivered as oral communication, and, therefore, may not conform to written grammatical or syntactical form.
I am very satisfied with the services rendered by Mr Khanna and his colleagues. They have been professional and quick to reply to most of my emails and calls. I was not very involved with my Green Card process as my work is quite hectic so it was specially good to have people who are abreast of rules and regulations. They had the foresight to indicate CP on my I-140 application which saved me at least few months. I strongly recommend Mr Khanna to anyone who wants to get their GC process done in a smooth, streamlined manner.