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:
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.
Ask your pool operator. Luke-Jr, the operator of Eligius, has been quite transparent about his objection to P2SH and decision to record a "no" vote in blocks mined by his pool.