I've been on nominating committees for various organizations, and we generally saw our role as "previewing" candidates before the large group voted. When names were submitted by others, as opposed to people nominating themselves, we always called the individuals to verify their willingness to hold the position if elected. We also called everyone (if they didn't show up in person at our nomination meeting) to ask about prior experience they might have, that would be beneficial for the post they were now running for. We'd create a short written summary for each candidate, and then let the general membership make the final decision by their voting.
If your school is really starting a PTA, and not a PTO or Parent's Club, there are national bylaws and guidelines your school will have to follow....someone might want to join Greatschool's PTA group at community.greatschools.net/groups/51536

Very good question. How do you even know the nominating people want these jobs for which they've been nominated?
In any case, you're left to hope that others on the nominating committee will know and recognize some of the names. Or - do it like a democracy does and if there are people whose names have been nominated more than other people,treat the nominations like votes and so award the jobs to those with the most nomiations.