A year ago, I had to do this paperwork, plus open a checking account, for a different type of non-profit. I was the newly-elected Treasurer of the new organization. You can apply for the EIN online and you get a number and letter pretty much instantly. But I felt quite intimidated at having my name on the paperwork, so I understand your quandry. It will need to be someone who is a responsible party in the newly formed organization. You have to provide documentation of being the responsible party duly elected in order to document having a non-profit account, if your bank is like mine.
I would like to know if there are any set rules for who can change a meeting date? Does it have to go for a vote or can the officers decide, more importantly, can the president make that decision?
Yes, if you won't be treasurer of the new PTO, then I'm pretty sure you cannot sign the 501c3 application. It should be an officer of the new organization -- and it will likely take several months for the IRS to process your application, and if the IRS has any questions, the new officers will need to answer them.
Being that there are two of them and only one of you, and that you (I'm assuming) have stuff to take care of already in terms of closing out the PTA books, I don't see anything wrong with you telling them that they will need to take this on. The process of doing these things isn't always a short one, and as you may not be around for the entire thing, it would make more sense for someone who will be to take it on.