HaKatan,
1. “One who has been killed by non-Jews is buried in his clothes, so that his blood may be seen and avenged… In other words, the clothes of the Jew acquire a certain sanctity when spattered with the blood of a martyr. How much more is this so of the Blue and White flag, which has been immersed in the blood of thousands of young Jews who fell in the War of Independence defending the country and the population… It has a spark of sanctity that flows from devotion and self-sacrifice. We are all enjoined to honor the flag and treat it with respect”, (Rabbi Soloveitchik, Five Addresses, p.139). This certainly not true of a football team. So far as America has shared values with Am Yisrael (this is an essay in itself) fighting for America, especially in WW2, might give the flag some special significance but not kedusha as it is mainly a non-Jewish symbol (don’t forget, Jews make up less than 2% of the American population).
2. “Something like”? Rav Tzvi Yehuda (Kook) said that religious Zionism is a redundancy because our religiosity makes us Zionist and our Zionism is rooted in religion.
3. Who says?