Yes, it is an illness. To get rid of it, you need to see a therapist, preferably a behavioral therapist. Depending on what you are obsessive-compulsive about, your therapist will instruct you to do certain things that will condition you to not act on your obsessive-compulsive impulses.

Related to self harm? I don't think so.

YES and it's hell.

Most people with the actual disorder have issues stopping it themselves. The obsessions and compulsions are strong so they seek therapy. Therapy involves around how to channel the anxiety from obsessions so they don't turn into compulsions.

Eh, not really.

I strongly recommend checking out http://www.ocdmesh.com./ It is a great online support group and source of information about Obsessive-Compulsive Disorder.

Visit a psychiatrist