It sounds like you have gotten off to a rocky start with the new staff person. I don't think that it is reasonable to schedule a conference call 12 hours in advance unless it is an emergency call. That being said, I would let him know that you think the calls are a good idea but that you need more lead time and cannot participate tonight.
Aside from the phone call it sounds like you are holding the fact that he is a staff person against him. Having worked in and volunteered for nonprofit organizations for 20 years I can tell you the vast majority of employees "care" about the organization or they would never work there as the pay is generally not great (don't know your specifics). The staff/volunteer relationship can be difficult to navigate. As a volunteer you think he is really nitpicky about paperwork and he lost what I gave him and as a staff person he is probably thinking, I can't believe I can't find this paperwork and if it is not done it is my rear on the line not the volunteer. If it were me in your position I would ask for a meeting to outline your responsibilities and his, so that you both are comfortable. Good volunteers are hard to find and I am sure your new boss knows that. Hope you are able to find a way to work together!
Kelly
DS 1 12-02
DS 2 12-04
DD 07-08