You're right for 1, 2, and 3. For 1, I assume they mean solid NaOH, and not aqueous NaOH. You are right that ionic bonds are not "intermolecular" forces, but they are what keeps the Na+ and OH- ions together. In that sense, their function is the same as the intermolecular forces that keep molecules together in molecular solids (e.g. ice).
For 4, what answers can you eliminate based on chemical intuition?