Always record females using their maiden names.
The National Archives and Records Administration (NARA) in Washington, DC and its Regional Branches, is the principal repository for records relating to the US federal government. These include the original paper copies of the federal census, all pre-World War I military records, Native American records, military service and pension records, naturalization records, ship passenger lists, land-entry case files, and homestead and bounty land warrant records. NARA's website is the place to begin research for federal records.
The 1900 through 1930 censuses lists the individual's year of immigration to the United States. Don't be surprised if they are all different dates.
The Family Group Sheet identifies a couple and their children. Everyone with a spouse or child has two group sheets; one as a child with parents and usually one as a parent with children.
The USCIS Genealogy Program is a fee-for-service program that provides researchers with timely access to historical immigration and naturalization records of deceased immigrants. https://www.uscis.gov/genealogy