Any "member" of our PTSA can vote in elections. This would include any member of the faculty (teacher/administration/lunch lady) that chooses to pay ($8.00 to join) to join our group. However, each vote counts equally. If they have not chosen to join, they do not get a vote.
Out going board members can vote and I've honestly never seen them not vote. However, many boards to not allow the principal or vice principal to vote. I feel that gets tricky if they have children within the school, because they're participating as a parent as well as supportive administration.
It really depends a lot on your current by-laws, so your best bet is to check them first. At the last meeting of the previous school year, everyone who was present voted, with the exception of the principle. He felt it was unfair to vote when he wasn't familiar with all those running. He was also retiring, so that may have played a role as well.
Any member of your group can vote, including outgoing officers. Personally, I would draw the line at the principal or vice principal having voting privileges, unless your parent group/by-laws specifically give that privilege.
I may be in the minority, but I firmly believe that administration plays a supporting role in parent groups so as not to have undue influence.