I have mixed emotions about this. The courts allow arbitration on a multitude of civil proceedings based on relegious canons or halakha or shariah, etc...
but something doesn’t seem right about letting Muslims getting a foot in the door of our legal system, when they have avowed that they want shariah to be the supreme law of the US., where halakha and canons do not espouse that.
The U.S. Constitution is not a suicide pact.
I think you mean approx. 2.5%.
The US Census Bureau, while not allowed to ask about religion, does collect data from self-described and it estimates that, as of 2010, Texas has a Muslim population of 581. and estimates the U.S. has a Muslim poulation of approx. 7 million.
http://www.census.gov/compendia/statab/2012/tables/12s0075.pdf
As for your last “further” ? I agree...in spades.
Unless we are going to modify the 1st amendment with a clause allowing government to define which religions are acceptable, and which are not, I don't see how you prevent people who decide to practice the muslim faith from building houses of worship, or entering into contracts that are based on their religious beliefs.