Yes, you need a treasurer, an outreach person and maybe a chairperson to oversee everything. This clarifies job scopes and responsibilities. It definitely minimises overlaps and increases chances of things getting done.
However, beyond GETTING THINGS DONE, remember that the people you serve and the people you work for are just that – people. Individuals just like you and I, with multitudes of experiences, personalities, tendencies and highly individualised hopes and desires.