Flour can be made from many types of grain or bean. Wheat flour can be several different grades of flour. Whole wheat is just that, it's the whole grain ground into flour with nothing removed.
Not really, wheat germ has a different flavor and texture than white wheat flour. If only a small amount is called for some whole wheat flour may work.
No. Wheat germ is a specific part of the wheat grain, containing oil and other nutrients, without the starch of the rest of the grain. Flour is the starchy part of the grain with bran and germ...