yes
No. first of all because when a person is already married cannot marry another, unless he first gets a divorce from 1st. spouse, after he is divorced he may marry but if its for the purpose of getting legal residency immigration law prohibits it.
your now wife get a temporary green card for 2 years. after 2 years both of you have to go to immigration and renew it. they have to make sure that you guys still married so she can have her permanent green card.
Marry someone
Yes. When applying for a NYC ID card, no one will ask for immigration status or proof of legal entry into the United States. The residency requirement does not call for proof of legal residency.
you can marry but it is no guarantee if they will become legal. You need to understand even if children are involved you are looking at time and money. if your spouse entered the country illegally they will have to return to their homeland at some point of the process (unless the laws change) and then depending on how long they have been in the u.s illegally, they have the option of denying them re-entry for up to 10 years. You need to know this.
yes
No
That depends on the motives of the green card holder ;)
Yes, you can marry in Tennessee but I do suggest you file for his residency immediately after the marriage as it can take a year or longer to get his green card.
Yes. Some US states permit same-sex marriage, neither citizenship nor residency is a bar to marriage, and the US federal government does recognize same-sex marriages for the purposes of immigration, effective June 26, 2013.
Yes, but the US citizen should sponsor his/her spouse's immigration in order for him/her to get a green card.
This person is still an American citizen and should have no problem re-entering the states if he wishes. I would of course suggest checking with someone from U.S immigration services first