Do you feel that a postpartum support belt is helpful for necessary?
I have never used one personally, and have never felt I needed one. I do know that many moms like a belt that gives gentle support and shaping, so if you think you would there's no harm in it.
It is important to use some sort of support belt or an exercise band when you first begin exercising your abdominal wall. Your abdominal muscles have separated some due to pregnancy, and it's good to use the band to keep them pulled together as you gently strengthen your core.