No. Inattentive add will respond to much the same medications as adhd, although with much individual variation, and yes., some kids only improve with medication.
No. Children who are predominantly inattentive respond to the same medications, methylphenidate (Ritalin or Concerta) or amphetamines (Adderall (dextroamphetamine and racemic amphetamine) or Vyvanse) as children who are hyperactive.
No. I find that medications are not necessary. Often the problem is a medicl or processing problem that can be successfully treated and no medications are needed and no adhd label is needed either.