How can one know which way mining pools will vote for P2SH? Is there a list somewhere showing how each mining pool will vote on the P2SH question?

and

If a pool says that it is voting one way, is it possible to independently verify that they are indeed voting that way with their mining power?
You should check out this page:

http://blockchain.info/p2sh

If you want to verify if a given pool operator has indeed mined the blocks for the votes, he or she can sign some message with the private keys corresponding to the public addresses that were the recipients of the block reward.