1. Given that anti-Muslim feelings are stronger among Republicans than Democrats, that number 2-1 for Democrats seems about right.
2. Defining a Muslim, like defining a Jew, is tricky. Most Americans would say anyone from a Muslim (or Jewish) background who is not a Christian is therefore still a Muslim (or Jew) even if they aren’t very religious.
3. Most Muslims who came to America did so in the hope of assimilating into a majority culture where they will be free of many aspects of Islam (same for most American Jews).