Is it permissible to travel to the United States for work and study with the intention of returning to serve Muslims, and does this contradict the principle of Al-Wala' wal-Bara' (loyalty and disavowal), and is sin incurred from taxes that might be used against Muslims?

If you are secure from temptations and are able to observe the rituals of your religion in the lands of the disbelievers, and you cannot acquire the knowledge you seek in the Muslim lands, then there is no blame upon you for traveling to study in America or elsewhere. Then you should return to the Muslim lands after fulfilling your purpose, in order to benefit them.