Frontend wobble or oscillations could be caused by any of the reasons you've given. In addition, worn tires, worn or loose swingarm bearings, damaged rims couls also be possible causes. If you are experiencing front end wobble and you are looking for advice how to solve it, then start with the easy things first (like loose steering head bearings, loose clamp screws, check swingarm for looseness) before moving to harder things. Process of elimination.