Worship God.
I expect his religion is Islam as both names Tarik and Ramadani are Islamic names
With tolerance, an open mind, and understanding. You would expect them to tolerate your religion, so you should do the same for them.
Because it you decide to change religion you know what to expect
It is fine as long as it is clear with them that your religion is your beliefs and your lifestyle as well and that you would like for that to be respected. Depends on how serious it is. if we are talking marriage Muslims for instance expect you to convert.
Books on this subject are several hundred pages long. You cannot expect that much information in this space.
In Australia Not many people particularly care what religion you are or for that mater if you have a religion at all. politicians put on a bit of a show that they have a religion but this is more to attract a few votes then anything else. government and public service appointments are never made as a result of religion. We like to treat those that treat us well and we expect the same from others regardless of religion. This is Why we have the most stable political system in the world.
The Caliphs were the functional equivalent of Kings and did many of the things we would expect a king to do, such as declare wars, set legislation, organize the state, direct religion, etc.
I have been in this situation. The best thing you can do is accept that your beliefs are different, and expect her to accept it as well. As long as you both can do this, there will not be any problems with it.
Daniel Bedingfield is a Christian, yes. Wikipedia quotes him as saying the following: "I find that when people hear that I'm a Christian they expect me to be extremely religious. I'm not great friends with religion [although] I'm passionate about anything to do with God."
Most immigrants expect to have more freedoms of religion and a better economic life. They want to live a life better than their lives before. In general terms, immigrants do and have in the past found that the USA offers them more opportunities then their former homelands.
Christmas is basically a Christian holiday: the celebration of Christ's birth. So, I would expect non-Christian religions not to celebrate it (they have their own holidays).
In Thailand, a Therevada country, the religeous hierarchy is also a significant part of the political heirarchy. The two are intertwined.