After your 2 year UC expired for your spouse how long it take them to become USC? (if they make any visit during that 2 year time frame to forgein land does that count? Means does that get minuse for 2 year time frame?)

He can apply for Naturalization after 3 years when he first get his green card (if the petitioner is a USCitizen)

When can I apply for United States citizenship?
A...As a spouse of a US Citizen, you can apply for citizenship 3 (three) years after approval of your Adjustment of Status. Back at the AOS interview, your passport was stamped with the I-551 stamp and a date. The 3 year countdown begins with that date. This 3 year period does not include long absences from the United States.
If you came to the United States on a K2 visa, you can apply for citizenship 5 (five) years after approval of Adjustment of Status, as only spouses of US Citizens are eligible to apply for Naturalization after 3 years. However, if a K2 is very young, it is possible that they may be naturalized along with the parent, if the parent becomes naturalized before the K2 turns 18.