Stalin wanted the US and Great Britain to open a second front in France because it would divide the German military. During the time of this statement, Germany's only real military threat came from the Soviet Union. With this in mind, Hitler had the ability to put a huge number of troops on the Soviet Union/German border.
However, if the US and Great Britain planned an invasion through France, that means Hitler would have to move hundreds of thousands, maybe even millions, of troops to France. France, in relation to the Soviet Union, was over 1,000 miles away.
Forcing Germany to fight this two front war would decrease their chance of success.
Yes they can If the government has a compelling interest it is seeking to protect, and the fundamental right the government seeks to restrict is fairly and narrowly regulated by the law in question, the restrictive law may be upheld by the courts.
