If you have by-laws and they don't include a vice president, I'd start with revising them so that there is no confusion. Part of this web site under, I think, the tax and by-law heading, is a subheading called lots and lots of sample by laws or something along those lines. Our VP is charged with coordinating the activities of all fundraisers - that doesn't mean she does them, that means that she acts as a liason between each fundraising committee chairperson and the executive board. She is their chaperone as our communications/social activities coordinator is the "chaperone" of each chairperson of a social committee, etc. If there's anything else I can help with (not that I'm assuming I've been helpful) let me know.
Our school started two years ago and we just formed a Parent/Teacher group. We included 3 VPs, one to monitor fund raising, one to monitor volunteer activites, and one to work on membership and communication needs. In order to determine this, we wrote down all the projects and activities we would like to have at the school, then grouped them into what turned out to be three categories. We'll see how it works.
Good luck. A word or wisdom about passing a job onto someone else, sometimes you have to accept the job they do. That's the hard part about delegation. A good President will enable others to do the best they can, but don't ever expect it to be just like you would do it.
I am a co-pres of a Prek-G3 elementary school. My co-pres and I are doing fairly well getting volunteers to work our events but we would dearly love some help with the prep work and planning phases. We thought we might "advertise" for a VP or co-VP and post a job/responsability description. What do you VP's out there do? Let me know.