The Torah, including its accompanying Oral Tradition (the Talmud).
Orthodox follow halacha; Reform don't.
Yes. They still do.
Orthodox Jews generally follow a custom of never setting foot in a house of worship for another religion, though there are a few Orthodox Jews that will.
There's no exact number, but it's mostly Orthodox Jews who follow the dietary laws.
The Mosaic Laws are the laws that God gave to Moses. Jews are supposed to follow these laws to the best of their ability as a guide to being a good person and a good example to the people of the world. Jews who strictly follow the rules are simply religious Jews.
Hasidim are a portion of Orthodox Jews. They follow Judaism on a strictly Orthodox level.
Orthodox Jews follow nearly all the laws. Conservative follow some, but not all. Reform Jews follow little or none of the laws.
They should follow in the ancient traditions of Judaism (the Torah) exactly.
It depends on which denomination within Judaism you are talking about. Non-Orthodox Jews generally follow the customs and social norms of the society they live in. Orthodox Jews vary. Strict, "ultra-orthodox" Jews have no dating at all. They generally rely on parents or other family to help find potential spouses. Modern Orthodox Jews may date, but it depends on the family and some families will require a chaperon.
The answer completely depends on the Reform Jew you are talking about. Orthodox Jews follow all of the laws (no driving, cooking, etc) and some Reform Jews do the exact same thing.
Orthodox Jews follow strict tradition and Jewish law, whereas the Conservative movement has relaxed some of the observances.
No.