This is still not enough for population growth.
See fertility rate as a "fitness function" of the respective country. Higher is better, even it is below threshold of replacement (about 2.1 in technologically advanced countries).
Any problems with the population easy to control due to migration. I do not understand why migration has become a problem. If competently approach to this problem it is possible to provide the country with cheap labor.
Do you want the last words you have heard in your life would be "Allahu Akbar"?!
So if a guy from Holland comes and smokes crack in America our laws don't apply to him because his laws allow it?
Should a guy from suadi arabia be able to kill his daugter in America because it is legal for him in saudi?
Can I go sell AR-15s in Mexico and Germany because it is legal for me here in the USA?
For some basic laws which are universally known (murder, theft, rape using physical violence /except b*shit "statutory rape"/, vandalism) it is not a problem. They are illegal no mater of jurisdiction.
For other acts, person cannot be punished before he signed a contract with the visa-issuing government that he knows and understands ALL laws the govt wants to apply to him! It must me informed consent, well explained by visa officer and the officer must ensure if the visa-asking person really understand these laws.