Soba noodles are made from a combination of wheat and buckwheat flour. You can also purchase 100% buckwheat soba noodles which are fine for gluten intolerant folks since buckwheat is not a relative of wheat and has no gluten content.
There are many good brands. Eden Foods is one of my favorites. They make several varieties of soba. Wild yam soba has (duh) wild yam added which is an herb thought to promote longevity. It has a light tender quality to the noodle. Mugwort soba is sort of olive green colored and has mugwort added which is an herb thought to support the female reproductive system.
Best to follow package instructions to cook them. They usually only take about 7-9 minutes of danicng in boiling water.