We usually take around £100 worth of pesos which we buy at home and then change English pounds to pesos as we need them at the Mexican bank while there. I've taken US dollars in the past, which you can use in the shops etc. but everything cost more in dollars than pesos. We usually walk to Playa del Carmen from our hotel in Playacar during the day and taxi back. From reading recent reviews it will cost the equivalent of £4 to £5 for a taxi back. It's too hot for me to walk on an evening if we are going down to town for drinks so a return taxi will cost between £8 to £10. I think the Riu Lupita will be either the same distance or a bit longer into Play del Carmen town. Drinks were pretty much the same as in the UK so factor in around £4 to £5 for a spirit and £2 to £3 for a small beer.
I think trips will cost around £100 and around the same into Coco Bongos. A meal will vary depending where you eat but I would factor in around £30 each per meal.
Sorry I'm giving these prices in pounds but I can't see what nationality you are and we usually work everything out in the comparison of UK pounds.
There are some lovely shops and stalls in town and you can get some good quality t shirts and costume jewellery. Remember to barter at the stalls though because they will often give you an initial price marked up by almost 100%. Have a wonderful holiday