Yes. Personality disorders start in early adulthood and are often hard to treat. There are no fda approved medications. There are numerous skilled therapists who are adept at various psychotherapeutic techniques that can help you realize how your behaviors impact you and those around you. Through self reflection, some of the behaviors can be changed.
Narcissism Tx. Schema therapies, skills training, relationship therapy, group therapy, and medications for anger/rage/impulsivity.
Perhaps. I'm a believer that anyone can benefit from treatment if they want it. "if they want it" being the key phrase here. Individuals with narcissistic personality disorder are notoriously difficult to treat, as they oftentimes don't think they have a problem.