just to help you with the dollars/pesos confusion.
I CAME BACK FROM THE RESORT THIS PAST MONDAY,our wedding was amazing,I am working on the review.
We booked with Thomas Cook in England and were told in writing to bring PESOS.
So we did,only to find out upon arrival that what it was supposed to be a new law fully implemented its not and EVERYPLACE IN THE RESORT WILL TAKE YOUR DOLLARS.In fact,prices in the shops and spa are in dollars.The wedding coordinator will talk in dollars,the photo prices are in dollars.
Now if you do have pesos they will take them also.
We figured eventually the country will switch over to pesos as it should be.But in the meantime I wouldnt worry too much.The hotel has an exchange desk and the rates pound-pesos were the same I got in one of the best bureaus in the UK.
Good luck,let me know if I can help with anything.