Yes, they could think the marriage is just to stay in the country.
Yes. If the illegal immigrant marries a citizen, they can become a citizen from that.
only if the person marries a US citizen
If they're in the country legally, they should apply for US citizenship.
nothing she tills has to become a citizen
No rights gained, save for the ability to legalize your residency status if the immigrant entered the country LEGALLY.
No, marrying a U.S. citizen does not automatically grant an immigrant permanent resident or citizenship status. http://www.uscis.gov
Yes, they do. Why would an immigrant need to talk to INS about a marriage? Immigrant means they are already residing in the US legally as a immigrant.
No, she is not. She will be allowed to remain in the US with her spouse and children, but she will have to apply for citizenship separate from her marriage. The US citizen REMAINS a US citizen. The immigrant remains an immigrant and must follow the legal path to resident immigrant status, and from there to citizenship. Marriage is not a free pass to residency or citizenship.
He can be arrested as he is a illegal immigrant and he has got married before waiting for a year aftr getting divorced.
No, marrying a US citizen or a permanent resident does not grant the illegal immigrant legal status regardless of whether there is a child involved or not.
US Citizens can't be deported from the US. Any alien can be deported.
Check with the laws in your state before getting married, but in most states, anyone who marries a United States citizen can become a US citizen, and thus be legal.